It feels like they're recreating Cena/Triple H/Orton from 2008, with the champion going in as the underdog that nobody thinks can win and they pull off the upset. Rhea/Bianca was clearly the match they wanted to do, but they got cold feet and wanted Iyo to be in the title match, so they went with a triple threat.
If Iyo pins Rhea one more time, it justifies her winning the title and it humbles Rhea. She can't blame Bianca this time because she lost clean in front of 60,000 people and now, she has to reevaluate what she did wrong. It also protects Bianca since she still has the streak and it gives her a reason to get a rematch one-on-one.
But I wouldn't have a problem with Bianca winning, especially since it's going to piss the crowd off and expose their racism.