RDJ has said he has no interest in coming back to the MCU, however, I think once Marvel flashes the money, he'll be back. He had Doolittle, which I think lost a bit of money if i'm not mistaken, and what is he in next? Black Widow (remember, BW takes place before Tony dies). After that, he's got nothing coming up and the only thing he's rumored for is the Kevin Feige Star Wars movie.I think it makes for a good last hurrah for many of the actors and depending on the version, they could justify bringing back Iron Man which would be ridiculous but I don't care.
And then you film extra footage to have the Deadpool version and everybody loses their minds again.
I'm genuinely so excited about the idea.
If i'm RDJ, I stay close friends with Feige since he seems to love him and also learn to embrace the Iron Man character and just continue to cash in.