Losing JL weakens OW but is hardly a fatal blow. AA without ATI TATL and no partner TPAC is simply in a similar position to CO several years back when CO was actually at its best. Hopefully this will get AA focused on really getting the premium product where it should be. It will still be possible to make interline connections to either NH or JL via NRT. Folks flying on premium tickets will still get lounge access, they'll just lose the mileage on the connection which I bet for the vast majority of business travelers who make their plans based on schedules and cost barely notice since they probably didn't even know JL was part of OW in the first place.

As to the next defection from OW, I guess folks can start speculating about QF moving to ST