I still feel like perona will join the crew , I don't know why but in One Piece It feels like the main female characters kind of have to be somehow evil at first glance. Come on take a look at Nami , Robin , Vivi. So I don't know , maybe she will join. It's like " You purified my kumashii , you will become my new kumashii so I'm going with you :D "
But I think Usopp fighting her is really good I guess. At least with that , we may even see new bounties like Usopp The fearfull sniper 40milion and SogeKing 30milion. How would that be huh :D