How long until we see the writer's strike impact films?

We’ve already seen the impact of the writer’s strike on television that requires a regular, daily staff and we’re coming up to the February sweeps where the network should have been starting up the new episodes for the rest of the season, but when will films be impacted? It seems that a lot of the films for this summer have already completed the shooting (mainly due to a long post-production period). Will there be a lack of new movies come September?

We are beginning to. Warner Brothers has already postponed starting filming on one film (Justice League) because the film needs a rewrite. The film was cast and filming was supposed to start in the spring.

From Entertainment Weekly: