The Marvel Cinematic Universe's Phase 3 is set to come to a close with the fourth Avengers movie on May 3, 2019, and barely two months later, Spider-Man: Homecoming 2 will kick off Phase 4 on July 5, 2019.
Considering Hollywood's love of the three-act structure, it's widely expected that Phase 3 will bring the Thanos chapter of the MCU to an end and signal a major paradigm shift for the franchise moving forward.
Simply, Phase 4 is going to be a game-changer and prove whether or not Marvel Studios will be able to adapt to personnel changes, the increasing threat of creative stagnation, and a desire from fans for the various disparate strands of the MCU to be united for a giant cinematic event.
For better or for worse, it should show Marvel Studios taking a few more risks and shedding some of the complacency they've been accused of over the last few years. Whether it'll pay off remains to be seen, but it'll be fascinating to observe all the same...