I still remember shifting in my seat as the credits rolled on Avengers: Infinity War. My bladder was urging me to bolt for the bathroom, but I knew there was a major post-credits scene I had to see. The culmination of the MCU had a major downer ending, and ran nearly two-and-a-half hours, the longest outing to date.
Now, the end of Infinity War – which will involve Brie Larson's Captain Marvel in some way, who will be introduced in her own film just two months prior – laughs at all that. The Russo Brothers' big finale reportedly clocks in at three hours, making it one of the longest blockbusters ever, approaching the epic size (or bloat, depending on your view) of Titanic and The Lord of the Rings trilogy.
While this probably won't be the final runtime, it seems this cut is close to the real deal - unlike when blogs try to get clicks from reporting on "assembly cuts," which is just all the filmed scenes strung together in loose narrative order. That's just to help the post-production team know what to cut. This seems like they've got their epic finale in order, they just have to decide if that's how they want it. Considering there's no official title yet, they might not have anything figured out yet.
The last Avengers film opens May 3, 2019. Though don't be surprised if they bump it up a week sooner like they did with Infinity War.