With a budget of $400 mil, and Dune competing directly against it, if this movie ends up with average or sub par reviews and below typical BO returns, you’d have to think they re evaluate the Marvel business moving forward. If a movie this stuffed with characters both new and old can’t attract an audience enough to be a billion dollar blockbuster, no future film will (save for maybe Spider-Man).
That said - I’m still hedging on this being a $1-1.5 bil success. The question just becomes is it a success enough that they don’t backtrack from Secret Wars (which I believe has still not entered principal photography). A movie that will most likely be even more expensive as the ultimate transition film for the MCU.