Most likely candidates for closure are SCN and/or ZQW. they are currently in talks about both these marginal airports, which are not even half an hour drive away from each other.
KSF is brand new and is the state's government pet/toy... it will accumulate losses for longer. It has considerable business aviation.
MHG very important for business aviation, and just got back its link to Berlin. Too small a runway for LCC ops, but I think they are doing OK.
RLG and ERF are both enjoying strong state government support, as "flagship" airports for their respective states.
Other marginal airports that face issues include FMO, FMM and DTM.