The movement is not sustainable. The ideology is inherently flawed. I have yet to hear any convincing logical arguments to support trans-ideology. The best effort I've seen is the citation of studies on the "ladybrain" argument, but there are so few of those studies and they are so flawed, so the citation of junk science isn't going to cut it.
They will continue to alienate LGB people and while LBGT media and activism groups don't seem to care that their sexual orientation is yet again being invalidated, individual people will care and while it hasn't occurred yet, a rift seems inevitable (Drop the T!) A rift within transactivism also seems inevitable. It's already bubbling up in the truscum v tucute. If you can say you're trans without any form of transitioning, that is a direct contradiction to the position of the necessity of transitioning because your brain "doesn't match" or whatever.
I'm an old lady by Reddit standards. I think a lot of people who identify as trans or queer will grow out of it. It's a new form of teenage rebellion and self expression. When I was a teenager, it was certain music and fashion scenes to assert our individuality and freak out our parents. When my sister was a teenager, the alternative girls all identified as bi with bi being defined as making out with girls while you are drunk aka not bi, now we have this hot mess.
Men will not experience the same bullying that women do, however the "my penis is female, have sex with me" will not jive with a lot of men. But, most TIMs are heterosexual, so again, women will have to deal with that crap more. A lot of conservative men and anti-feminists who aren't specifically MRAs can see that trans-logic makes no sense. A lot of the anti-feminist stuff I have seen is actually anti-stereotypical libfem. I don't think they'd like fully embrace GC or anything, but there are people on both sides that see this is completely bonkers.