Unless Gareth Bale offers are coming in Jan he isn't getting sold. And yes selling to Barca would be nice, we can maybe get a loaner or two in the coming years and hopefully get the Gerard buyback erased.
He won't be here next season (unless injury) and that's OK. CB is one position in which you can develop and with good scouting find pretty good ones cheap (England CBs: Smalling rumored 7M, Jags 4M, Cahill 8M, Stones 3M, also Scott Dann didn't cost Palace much either). You sell Rom for 40M and you most likely got to spunk 25-30M just to find a suitable replacement. Sell Stones for 40M and you can find a quality CB for 10M.