Isco would be a replacement for Nasri most likely. Txiki identified him and Benat (Betis) as his two primary targets when taking his DOF position.
A lot of other names have been mentioned in passing but Isco and Jovetic have dated back to last summer (or before). Pedro Obiang (Sampdoria), Mauro Icardi (Sampdoria), Marquinhos (Roma, CB) have been mentioned quite a bit this season. Some others from Roma (Lamela, Pjanic) have been linked -- don't think DDR is ever going to happen.
Forgot Samir was on the way out potentially.
DDR won't happen I don't think, he's a one club player.