The Stark family is so OP that they're going to have to get as convoluted as they did with Dany's armies to even make it a challenge, so yes, I wouldn't be surprised if Arya dies in some retarded fashion. They can't kill Bran because they had 6 season long story arc about him becoming the three eyed raven and he hasn't done shit yet, and they already killed Jon so doing it again would just be blasé, Sansa is fucking irrelevant but maybe they'll kill her at some point for the emotional impact but that wouldn't make Starks less OP.... Arya on the other hand is the most overpowered of them all, literally being able to kill anyone she wants with ease, so they have to A) make her retarded or B) kill her off. They've already done a bit of A), we'll see if they go with a bit of column B) as well.
Her death would make sense as well because she's already achieved a lot with her training, killing off a lot of the Bad Guys in the series, and even taking out the whole Frey family. What a neat way to tie off that plot line -- 30 seconds of Arya going "lol ur all dead" and bam, no need to devote half a season to how a massive powerful family gets wrecked by what would have to be a huge army and probably a prolonged siege. Thank you for your service Arya, exit stage left.