Nothing and they won't because bitcoin is not stable enough it can still be manipulated you still don't know if a giant amount of bitcoins are lost or just held

Nothing and they won't because bitcoin is not stable enough it can still be manipulated you still don't know if a giant amount of bitcoins are lost or just held by an unknown entity. No, sane central bank would ever adopt bitcoin. It might be a cryptocurrency in the future but it will not be bitcoin.