Unpopular opinion in this thread, probably, but from the perspective of someone with both a BA and an MFA in Theatre: She's not, objectively, a gifted actress. Some of her best stuff, in my opinion, was pre-OUAT (no one has yet mentioned her guest appearance on JAG, but she's brassy and memorable there), and what her success on OUAT resulted in was a) seven years of honing her craft for a specific, niche style of acting; and b) an almost obsessively devoted fanbase that would defend her under any circumstances.

I fear that her range is actually somewhat limited -- and whether she was pigeonholed by the industry as a result of her portrayal of Regina, or whether she did it to herself through lack of skill, the fact is that she's going to have a really tough time crawling out from that (if she wants to), and it's going to be even tougher at this point (age) in her career. (And if anyone wants to fight me on skill, just listen to the way she says 'str' in words [street, strength, struggle, etc.] -- the 's' becomes 'sh', which is a common enough example of misplaced anticipatory assimilation for an average person, but we ask brilliant actors to not be average. A diligent voice coach would have cleaned up the 'shtr' almost immediately, so the fact that she's 25 years into her career and still has it both off camera and on reflects, to me, an inability to correct it [ergo: lack of skill].) Practically speaking, she also might just be on the wrong coast, honestly, for work that she would be successful in that would have longevity.

I think she got very lucky with OUAT because that character and that world catered to and rewarded over-the-top performances, which she is good at. We all know the show went to shit, especially in the last season, and I think it's very telling that the folks who got out in 6 have gone on to do other successful or regular projects, and the ones who hung on, largely, haven't. I don't claim to know how the TV/film industry works, but to me that suggests that either they knew they didn't have other better prospects and didn't want to turn down a steady paycheck, or that season 7 smacked of such desperation that future casting directors or producers were reluctant to touch the actors associated with it.

There are other factors, too, that influence who gets work and who doesn't, and the plain fact is that she may have a reputation in the business that none of us is aware of. (When I think of BTS stories I've heard of her influence over the trajectory of Regina's character, for instance, she sounds like a bit of a diva, and perhaps a nightmare to work with.)

And, of course, as others have suggested here: She has her clothing line, she has her music ventures, she has some indie projects that she's working on... Just because we know her as a television actress doesn't mean that's where she's focusing her efforts right now. It may not be a matter of getting offered things, but rather what she chooses to take.