On a side note, if Capcom does make an X9, it's gonna be a cheap product with no passion. It will be another "back to basics" mission pack recycling sound effects for nostalgia like Megaman 9 did.
This is the crux of the issue. No fan should want an X9. The odds are extremely high that it will be slop for a myriad of possible reasons.
Reason one, back when MM11 was made, there was a dev comment to the effect that no one had the "confidence" to make MM games after Inafune was gone. This is a polite way of saying that nobody wants to do it. Mega Man Zero especially has this problem, its fans are loud but it does not make the cash to justify making anything for it.
Reason two, the fans themselves. The reality is that over the years, most fans only remember Zero's half of X4, the Hunter vs Hunter fight in X5, and to an increasingly-lesser extent X1. That's why, on DIVE, the only playable Maverick was Magma Dragoon, and Iris got the third highest number of alts at like seven or eight versions. Double didn't get in at all.
That's why most crossovers are basically a rehash of X4, usually throwing in Zero's meme scream and heavily implying that Iris was extremely important to him. This culminated in DIVE's last event practically showing that she had his balls in her purse, he was that simp-y.
What does this mean? This means that there is an outsized shot that we will get fanfic as a game entry. Do you want to risk the chance that Capcom, which is going more and more woke, throws a bone to fujos or the other camps? I wouldn't.
The overfocus on Zero's half of X4 also means any future entry would try to reference it as much as possible. To wit, the X Dive artbook recently showed unused concepts, one was this:
Anyone who played X5 on would be forgiven thinking this was Alia in a Signas-inspired outfit. But no, this was labeled in the book as early concept art for the Iris Another alt. Do you see a speck of Iris in this? It was almost certainly swapped over to the more popular waifu, which ended up being unpopular in especially Japan because the Iris Another alt did not act uwu cute like Iris normally did.
On a different kind of dour note, the Dive OC Droitclair was swapped over from a more visually-interesting black-and-blue clown motif to some weird goth girl who is an inch away from showing an upskirt. Another OC, Final ViA, went from somewhat more evil-looking Sigma-inspired variants to a bishonen for obvious reasons. In the case of Christmas iCO, her key art went from her carrying gifts to showing off a pulsing womb tattoo.
In other words, they were blatantly trying to attract coomers with waifu and husbando bait, and they mostly try to reference X4.
I hope I have made my point clear here. Nobody should want X9 in this kind of environment.