What had previously been announced as Avengers: Infinity War Part I and Part II are now Avengers: Infinity War and Untitled Avengers Project.
I have to say that's a terrible name for the fourth Avengers film. But it does indicate there's been some serious retooling made on that third film.
Could it have just been too expensive? And that fourth film will eventually be renamed as Avengers: Dude Where's My Quinjet to save on the cash?