Interesting idea.  But as much as I may appreciate them, I have questions about whether those actors, at the ages they are at, could carry a Star Wars film as the lead characters at this point.   Look at Indy 4 with Harrison Ford as an example.  It made its budget back but not tons more.  My thought is that it would take a great Star Wars story around which they could be positioned, maybe not fully lead themselves, to make it happen successfully.   If I could get Luke, Leia and Han in a great Star Wars story, I'd take it.  But I don't need to see them in Star Wars again for a box office flop just to see it.