Eh-just make a CGI fest with de-aged Luke, Han, and Leia (Billie Lourd has already done fill-in work for Leia) and have Thrawn as the main baddie. Throw in characters from D+ shows and BOOM, there you go! People always wanted the trio together for one last romp through the galaxy. Do it. Filoni and Favreau are already most likely planning to do it for D+ anyway, what with all the rumors of Mando, Ahsoka, and Skeleton Crew tie-ins with Thrawn. They've already de-aged Hamil/Luke, with better results the second time and it looks like they are doing the same for Ford in Indy 5.