The Flash Season 7: 9 Theories On The Identity Of The New Big Bad
8. Sue Dearbon
This one's a bit of a longshot, but it's not impossible given that we are talking about The Flash here.
The recent developments regarding Hartley Sawyer's firing has left the show in a little bit of an uncertain place. Given that the following season was supposed to pick up immediately where its predecessor left off, it's going to be rather difficult to explain why Ralph is no longer part of the show (unless they recast) and the one character who could end up suffering the most is Sue Dearbon.
Introduced as a future love interest for the Elongated Man, Sue's arc was directly tied to Ralph all season as the P.I. aimed to protect her from Joseph Carver and his crew. However, she soon proved that she didn't need any protection as she held her own and fought off anyone who got in her way - and she wasn't afraid to reward herself with a few stolen items here and there.
It's unlikely that Natalie Dreyfuss will be written out of the show when she received such an overwhelmingly positive response from fans, so the creative team might have to come up with a new way of keeping her around. And, given everything that happened in the finale, Sue becoming a villain isn't the craziest thing that could happen.
Being wrongly accused of murder by the malicious Mirror Master is a pretty solid beginning for a possible descent into villainy so, bearing in mind that Sue has already committed some morally questionable acts in the past, it could work. Yes, it would be preferable if she remained on the side of good, but this would certainly be better than the show losing the incredible Dreyfuss too soon.