MM11 was safe so there's at least a reasonable chance the series won't be ruined.
Well, Mega Man 11 also had the gigantic advantage that those games barely have anything that could be called a plot. "Something happens, Willy is a cunt (be it obviously or subtlety), kill 8 robot masters" formula that I personally love to pieces and that allows you to dump out an entry without anything too hard outside of having to think of a 12th way to say "Fire Man" or not having to end up digging to deep in the barrel for Tupperware Man.
X is different, X became the super serial series (and yeah, X4 was the one that really went hard into that). 6 is the latest entry I played, but I have done my plot synopsis and the plot is convoluted shit when it hits 8, and that's ignoring what the Zero series establishes AND that 8 ended with a cliffhanger. How the hell are you supposed to follow that up? You are either already shackled by all the random lore floating around or you go "fuck it, reboot" which in this case I'd honestly go for the later, but then there is already a (shitty looking) X1 remake, do you just remake that again or do you reinvent it with 8 new Maverick designs? Maybe spice it up with Sigma not being the big bad? I could honestly get on board for something like that, but then we reach the other sad reality, Mega Man is a great mascot, but the fucker doesn't move units, so this wouldn't be helmed by a vet, it would be helmed by new blood with something to prove and those are basically a coin flip of delivering something great or absolute ass.
I'm starting to meander, but my point is that following up on X is a much taller order than with the standard series due to it's baggage and you are more likely to end up with a "spiritual successor" that plays like X but with a completely different narrative and robot master/maverick gimmick than actual proper X. And that's ignoring that playing like X has that big branch of Megaman or Zero playstyle, since they both have their followers but both require different game design to properly maximize.