I think they’ll just mutually agree to break up because they’re just not ready for this. They are friends, and could remain friends, but I don’t think either of them are actually attracted to the other. They were just mutually convenient practice partners they felt safe with. Even within that paltry definition of a relationship they’re failing miserably.
Also, you think Riku of all people deserves a redemption arc? He was in like 4 chapters and is one-dimensional as hell. Zero chance the author will do that.
I'm still against a breakup happening because Ueno and Moka are really trying hard to make it work and also a breakup could lead to Chisaki winning which I am wholeheartedly against.
As for Riku it's not about whether he is deserving of a redemption arc or not, it's just a likely path the series will take, Riku is in the same spot the bully trio was in, the girls are working on improving so it stands to reason Riku will as well if he is reintroduced.
There is a basis for him having a redemption arc with Ueno's comments and his sexfriend's comment.
If Riku comes back into the story it will be framed as NTRbait until Riku reveals he's not going after Moka anymore.
If Ueno and Moka do breakup I'd be content with both of them staying single for the ending but I have complete faith they'll make the relationship work.