We know that Marvel Studios plan on releasing Spider-Man: Far From Home as their next movie after Avengers: Endgame. However, what comes after those two seems unclear for now as Black Widow and The Eternals are still in the process of casting.
However, after the Disney conference at CinemaCon, a reliable source from Deadline has shared a rumour that sheds some light on what we should expect from Marvel Studios in 2020. They stated:
“Not revealed, what the Marvel movies will be for 2020 for the new merger. Word is that it will come to reveal itself after Avengers: Endgame opens at the end of the month. Rumours have been that it’s Black Widow standalone movie and Doctor Strange 2.”
As of right now, nothing has been confirmed but it’s believed that Doctor Strange 2 has underwent the process of its screenplay. It would make sense for it to have a 2020 release date, whereas The Eternals may need some more time as the casting process hasn’t even finished.