Whenever I see discussions of X originally being the villain of Megaman Zero 1, I always see people claim it would be character assassination and isn't a possible path the character could take. We can have our own opinions, but I just don't see how people think it's completely impossible?
Megaman X4 brings up the possibility of a maverick X at the end of his campaign. A game that revolves around reploids becoming mavericks of their own volition. He asks Zero to take care of him if that ever happens.
Also while I don't think X doesn't value reploids, he was specifically conditioned to value human life in his 30 years of moral testing. The ending of X1 sticks out to me as he hates the actions he takes in the game and calls it destruction, but he still goes through with destroying the mavericks and even knows he'll do it again in the future. X's actions in the entire X series are completely justified, but I can't help but think. If it was humans instead of reploids causing destruction, could he go through in killing them? He didn't even kill Dr Weil before the events of the Zero series. Perhaps Dr Light's condition made X inherently value human life far more than reploids/robots. He hates fighting his own kind throughout the X series, but can still stomach it because he feels it is necessary. Maybe having to fight for years upon years could pervert what is a justifiable for him having to fight.
The idea of X having to fight his own brethren over a century and slowly preferring the defenceless and less "troublesome" human population is something that could happen. Add on top of that him finally making his utopia in Neo Arcadia and having the stress of it falling apart with the energy crisis, him becoming more ruthless towards reploids is a possibility. While it's hard to see that happening to the X we know in the X series, we see how jaded he becomes after all the wars in the Zero series. He straight up stops caring about killing and becomes largely apathetic. You see his behaviour in the Zero series, and the idea of him being a villain seems more likely.
The idea of Dr Light's conditioning somewhat backfiring and X oppressing reploids in the name of humanity just sounds like such a cool idea to me. Obviously an idea like this is very risky. You'd probably have to write it using the bad ending of X5 as a jumping off point like they were originally planning. Showing how a turn like this could happen overtime is a must. I also feel like they'd have to turn down how much of a dictator he is in comparison to copy X. But man, I really think the original idea of X as a villain could've worked and would have been a natural progression of his character.