They haven't kept switching composers on the MCU films. The only time that has happened was John Debney on "Iron Man 2" taking over for Ramin Djawadi. Joss Whedon specifically requested Silvestri be brought on board "Avengers" so the film could retain a sense of musical continuity with Captain America. Far as I know Debney is still attached to "Iron Man 3" unless Shane Black decides to go with someone else. Patrick Doyle is supposed to return for "Thor 2". Although the composers for these films haven't been officially announced. Of course we don't know the status of an Incredible Hulk sequel so who knows if Craig Armstrong will return or not.
Patrick Doyle seems to be Branagh's 'go-to' composer so if KB isn't returning, he may not either. Shame, as I thought his score was the best of the Marvelverse.
Interesting that Zimmer, rather than Snyder's usual composer is scoring MOS. Does this hint at a Nolan-domination of the movie or is it just that Hans' experience with the Batman movies and his ability to score a rousing action movie was felt more appropriate for Superman's resurrection?