IMAX doesn't quite work like that, studios make deals months or years before their films' release dates for IMAX screens, since they're so limited. So even if Avatar is completely sold out in IMAX when the next big IMAX movie comes out (I think it's Alice in Wonderland?), it will still lose the majority of its showings.icarus-daedelus said:They're booked out weeks (months?) in advance. You might want to call up and reserve tickets.
Then again, Imax will milk this movie for all its worth, so it'll probably be there for a good while.