I think I can see Alan Rickman in a longish arc as a disaffected old school admiral on the way out, who along with "rogue" elements of Star Fleet Intelligence, provides a major threat to the Federation. Would make Satie and all of the other troublemakers look like small potatoes.
I could see that working if done right.
Also my sister saw me posting on this thread and asked if anyone thought that Ellen Page would be any good in a new Star Trek series? (Now that I've asked she's promised to quit bugging me LMAO