I think Spiderman, Doctor Strange, and Black Panther will get about 4-6 minutes in the third act, because they have solo movies. The rest of the dusted will have non-speaking cameos.
A-listers Boseman, Holland, and Cumberbatch were on set a fair while, and definitely have important scenes as they are popular solo movie characters, whereas B-listers Evangeline Lilly, Elizabeth Olsen, Paul Bettany, Anthony Mackie, and Sebastian Stan only filmed for a few days, with Stan not even sure if he is in the movie.
Guardians of the Galaxy will also be very limited to cameos as the Russo's can't do anything that would box in the incoming GotG3 director. Guardians scenes may have been cut to add more Black Panther scenes.
Almost certainly final MCU movie appearances of:
RDJ, Evans, Renner, Bettany, Olsen, Mackie, Stan, Paltrow
Possible Final MCU movie appearances:
Hemsworth, Bautista, Saldana, Gillan, Ruffalo, Rudd, Lilly, Douglas, Pffeifer
Avengers Team Post Endgame:
Captain Marvel
Black Widow
Black Panther
Doctor Strange
Spiderman
Antman
Shiang Chi