Yeah, Prince Xizor doesn't sound like much of a modern Disney-approved villain given some of the very dark things he says and does in the SOTE storyline, and besides I don't think a 17 year old book like that - no matter how great it is in the overall panoply of Star Wars
novels - would be on the list of any new projects, live action or otherwise.
SOTE is widely respected as canon to fill in part of the gap between Empire
and even got its own line of merchandising in 1996 and '97 (including a Nintendo 64 game), but I think Disney is probably going to steer clear of revisiting most if not all of the older stories and forge ahead with brand new ideas.
All that said, I'd stack SOTE up against almost any novel written and published today.