Other IBs like.... ? Everything is so fragmented that there was like a 0% chance "the community" would move over. Even without the hack, they could "move" today. It's easier just to stay on 4chan and bitch about jannies, CAPTCHAs and etc.
Like many members of the public, the inhabitants of 4chan are really, really good about bitching about things and really, really bad about doing anything about it. A casual read of /pol/ would have you thinking there's a new American Revolution afoot. However, the posters tend to be fat, poor, manchildren angrily posting from their parents' basement, waiting for them to die to get their inheritance. Since they never leave the house and spend all day shitposting, they are in no danger of doing anything. Of course, there will be the occasional sperg-out where someone from /pol/ decides to grab a pistol and shoot some place up, but let's be real, that's like a 0.0001% incidence, and no more common on 4chan than any other "community". Statistically, there have been just as many Youtubers who freaked out and shot up a place as 4channers.