unless Satomi turns out to be actually straight or has some huge red flags, I don't see how Kayo would choose Junko over her (assuming the story ends with Kayo and Junko together)
Agreed and, more importantly, we haven't seen any kind of indication that Junko actually cares about Kayo (or anyone else for that matter) in any meaningful way. Kayo hates her too but despite both of them being pretty cutthroat about work, Kayo at least has scruples about her methods and interest in other people beyond their usefulness.
Junko on the other hand hasn't expressed any kind of fondness for anyone that seemed genuine afaict, she only sees people either as tools or threats and uses them accordingly. Not a single thought spared for anything else.
So if these two are actually endgame for a "regular" kind of romantic relationship, then there's a lot that still needs to happen, with Junko's mindset more so than with Kayo's, i'd wager xD