I think it will be Kevin going up, as a pawn.
Ronnie's been going in a constant cycle with:
Jordan
Russell
Casey
Kevin
He will put Kevin up (or maybe Lydia) so he doesn't piss off the Athletes too much, since Kevin is so dispensable as a player, and doesn't annoy Jordan/Jeff either. Ronnie will always take the easy, spineless option.
Nominating:
Jordan = wedgie from Jeff and Jordan.
Russell = wedgie from Russell, and Jessie.
Casey = wedgie from Jeff and Casey.
Kevin = wedgie from Lydia. And maybe a half-hearted one from Jeff just because.