Like I said, I don't agree with that for Avengers titles because their purpose is to react to big events. That said, you're right as far as individual character series go, and on that front Marvel for the most part doesn't force them to tie-in.
For this event as far I can tell the only titles that will tie-in to it will be the three main Avengers books (Avengers, New Avengers, and Uncanny Avengers), Guardians of the Galaxy, Thanos Rising, and maybe Nova and Iron Man. That makes only 2 on-going character books that will tie-in, with both of them being involved with space already, and a limited series that's probably being made specifically to tie-in with the event. The only book you could really make an argument for not being involved is Uncanny Avengers, but I'm sure they will be involved with both X-Men and Avengers events going forward.