By December 18th, 2015 any film that is available in an Imax theater in North America will be removed and replaced with Star Wars: The Force Awakens. The last time that Imax agreed to this type of indentured servitude it was with the three Hobbit films, and they haven't made the same deal again.
At least until Lucasfilms and Disney suggested that Imax allow The Force Awakens to take over their North American theaters for a month — then Imax agreed.
Imax has plenty of money to make on this film, considering that The Force Awakens is expected to release in 375 to 400 Imax screens in North America. Imax Entertainment CEO Greg Foster won't comment on the deal with Disney, but is confident that the film will rake in cash saying, "Star Wars: Episode VII is the ultimate crossover movie — it crosses over to everyone." Because the film covers "everyone" plenty of people will see it and if it does too well, you can expect it to take over Imax for more than a month.