There’s a chance he could factor into in The High Republic initiative the franchise is working on, though it largely depends on how long Plagueis was around before Palpatine.
Since his creation in Star Wars: Revenge Of The Sith, fans have been interested to learn more about Plagueis.
The Sith Master found a way to cheat death, so it stands to reason he could have an unnaturally long lifespan.
Right now, the only canon thing about the character is that he existed, so the rest can’t be fleshed out until Disney decides to re-introduce him.