I'm surprised it took this long - all Harmonizers saw this coming, one way or another.
I think after "Summer" didn't become the smash she expected, Camila decided to stick around a little longer, and now that "Bad Things" has gotten pushed over "That's My Girl" she probably sees this as the perfect time. I think the other girls felt that it was coming now as well.
I'm very happy about this though. The other four girls didn't deserve to constantly get pushed aside in the vocal booths, in performances, etc. It was clear that management was pushing Camila to be the IT-girl of the group; it always bothered me, because I think overall, she's maybe the third most talented member? idk; but it certainly was unfair. The group dynamic was always so off with her too, and you'd be dumb if you couldn't see the tension between her and the other girls in interviews, etc.
I think now with this next album (which I'm anticipating will be the last, although I pray it's not) that the girls will feel more free than ever before, and each girl will get their opportunities to shine equally. I think this next album will be the best. I don't like the idea of them continuing under Fifth Harmony though - they should just make it Fourth Harmony.