The Rambo remake will reportedly revisit the source material, which means divorcing itself from Stallone entirely feels like the best bet.
That said, it’s probably for the best that Sylvester Stallone has opted not to return to the Rambo universe.
If he randomly showed up as Sam Trautman (originally played by Richard Crenna) or Will Teasle (originally played by Brian Dennehy), it would almost certainly take away from the film’s sense of immersion and feel like forced fan service.
So he’s not coming back, but he also doesn’t seem to have any issues with the prospect of a remake hitting the silver screen.