I confess that Season 5 was the season that really put me off OUAT. Not because of the Arthurian characters so much, just because it was a series with a potentially very interesting set up with the Dark-Swan stuff and it ended up just being all about Hook and Emma/Hook. I dropped the series after that, don't know if it ever picked up again.
But that said, it would definitely be interesting to see what kind of characters they would end up being under the curse. I did a bit of brainstorming, and put together some ideas below - warning, some of it/ most of it may not be entirely realistic as it's been a long time since I've watched OUAT, and some of them may not be entirely serious...
I sort of feel like
Mab would be almost too powerful to be fully caught by that kind of curse. I mean she's basically a goddess, compared to the OUAT characters who are just powerful magic users. You could argue Rumple/ the Dark One might be an equivalent, but bearing in mind that he WANTS the curse enacted so he can find his son, and he sets up a failsafe for himself within it, it's possible that he could have avoided it if he'd wanted to? So maybe she would be in a similar position to Regina, she'd be in Storybrooke and have no magic (because there's none there to be had) but she'd still retain her previous memories? Either way, I struggle to imagine her not being in charge of something. Maybe she runs the secondary school (or high school, since it's American), as I think we only ever see the school that Henry attends, which would be for younger kids - she can keep a lookout for any kids with potential as wizards (once she figures out how to bring magic to this stupid town), without having to do the boring day-to-day work of actually teaching them (she has far more important things to do, obviously, and who has time for teenagers?). Most of the pupils are scared of her. Pretty much ALL of the teachers are scared of her, barring one or two. She considers this basically the one-and-only perk of the job.
Frik is Mab's beleagured deputy trying to do the day-to-day administrative tasks of running a school that the headmistress cannot be bothered to do (which is basically all of them, except scaring the kids who misbehave). He is DEFINITELY as scared of Mab as the pupils, probably more so. The pupils are equally as definitely not scared of him. When he's not trying to put out fires (sometimes literal fires, though slightly fewer of those since Mordred graduated...), he occasionally teaches classes, where he inevitably turns up in his own full set of robes and lectures to his pupils at great length. He started an amateur dramatics group, which doesn't have a tremendously high attendance level, but does occasionally put on plays. He worked up the courage to invite his boss precisely one time. She glared at him until he backed out of the room in a cold sweat.
Morgan is a member of Frik's drama group. She had (still has) dreams of becoming a famous actress, but the early loss of her parents and a teenage pregnancy somewhat derailed her plans for drama school, and she's never had much luck in securing auditions outside of the town line. In the meantime, being part of the drama group gives her an excuse to act in front of an audience and wear a variety of fancy costumes. She and Frik fell for each other whilst rehearsing a romantic scene in Romeo and Juliet. These days their rehearsals are mostly an excuse for them to read flowery sonnets to each other and make out, which makes it somewhat awkward for the rest of the cast and crew. It's possible that this is linked to the low attendance rates. In day to day life, Morgan runs a beauty salon, and raises (see: argues with) her son Mordred.
Mordred is a recent graduate of Storybrooke High (or whatever it is called). He is going through what his mother terms "a rebellious phase", which has lasted approximately from the age of 2 until now. He's not unintelligent, and he managed to avoid getting excluded from school (likely due to Mab's soft spot towards him, a fact that mystifies the entire teaching staff), but an impressively long record of petty crime under his belt has not made him a particularly appetising prospect for most nearby colleges, so he is taking a "gap year" by default. Unlike most of his fellow students, he always found Mab more fascinating than terrifying. He is currently working at the school, which in theory was meant to help him settle down and earn money, but in practice is an excuse for him to pine after Mab up close. It cannot be said that he makes a tremendous success of working there, but since Mab likes him and Frik is sleeping with his mother, he has been rendered basically un-sacakable. In an attempt to keep Mordred out of harm's way (by which he meant "everybody else's harm"), Frik assigned him to work in the school's office answering phone queries. Phone queries started drying up after they were greeted with anything from sarcastic put downs to straight up verbal abuse. Mordred considers this a job well done, as it gives him more time to blast punk music obnoxiously loudly out of the office speakers.
Merlin is a teacher at the same school. He is the only current faculty member (unless you want to include Mordred, and Merlin usually doesn't) that is not scared of Mab, and will occasionally stand up to her. Other than Mordred, Merlin is the only person Mab seems to have anything like a soft spot for - since none of the teaching staff, Merlin included, know that he is her son, most of them assume they are sleeping together, a fact that Merlin strenuously denies. He himself is mystified by Mab's apparent favour. She keeps cornering him in corridors and talking cryptically about his "potential" and how he could be something much greater. He has no idea what she is talking about, and is never entirely sure how to reply. He suspects that she knows this, and enjoys winding him up. He doesn't really like Mab, but there aren't a huge number of employment prospects in Storybrooke, so he stays on at the school. He has considered handing in his notice and moving out to one of the farms surrounding SB, like his Auntie A - the quiet, natural life appeals to him. There is one other thing keeping him in the town itself, other than his job, and that is his friendship with Nimue. She's sweet and kind to him, they meet up for coffee and walks regularly. Merlin is falling for her but trying to talk himself out of it, given her vocation.
Nimue is one of the nuns in town. She gets along very well with Merlin, the local teacher, and much like him, she is absolutely falling for him and trying desperately to convince herself that she is not.
Ambrosia was Merlin's foster mother after his birth mother died in childbirth, same as in the film. She and Merlin believed that she raised him in a farm on the edge of the Storybrooke woods, a childhood that Merlin looks back on fondly (it being subconsciouly based on his real memories of his childhood with Ambrosia). She's another one of the few people who isn't scared of Mab. The two of them have history - half the time they see each other they're arguing. The other half Mab is inviting Ambrosia out for coffee. Look, it's complicated, OK? Besides, Ambrosia is one of the only people Mab can stand in this town, even if she can't remember who she actually is.
Vortigern lives in a big house near the edge of town and owns a local building firm. Everyone in town assumes that he must have made his money prior to this, because White Dragon Construction... well, let's say it's not got such a great reputation for actually constructing things. The less said to Vortigern about that stupid underground spring, the better. He has a serious rivalry going with his next door neighbour
Uther, which manifests itself in everything from moving boundary fences in the night to be very slightly further onto each other's property, to excessive Christmas Tree light displays (Vortigern doesn't even celebrate Christmas, dammit, he just really doesn't like his neighbour) to fighting. Mostly fighting, if we're honest. The two of them have been arrested multiple times for brawling in public. Vortigern's not sorry.
The Lady of the Lake runs a pet store. Well, it says pet store. It's floor-to-ceiling fish. And she doesn't actually want to sell any of them. I don't know whether she still has her memories or not, but either way, she ignores her sister, chills out in her pet shop and spends her days watching her fish.
Lailoken (Soothsayer) is an ageing hippy who lives somewhere in Storybrooke with his architect husband, everything is fine and nothing bad ever happens to them.
Apologies for any silliness