During an interview with Collider, Captain Marvel producers Victoria Alonso and Jonathan Schwartz confirmed that Marvel intends to release the full back catalog of MCU films in 4K over time. “We are going to remaster all of our films in 4K. We’re in the process of doing that, so it’s all happening,” Alonso said.
Disney has already released 4K Blu-ray discs for a number of the Marvel Studios movies, which I’ve listed below, but there are definitely holes in the lineup. Some of those will be addressed this summer, per High-Def Digest, with Iron Man, Iron Man 2, Iron Man 3, Thor, and Thor: The Dark World slated for 4K Blu-ray release in the coming months. Still missing are Guardians of the Galaxy, Ant-Man, and Doctor Strange.
MCU films currently available in 4K: