If true (big if) you have to wonder if Leistner could be leaving?
If Cameron comes in be can cover centre back too so we simply wouldn't need another central defender... unless Leistner is moving on. He clearly isn't Warburton's first choice and there have been rumours of him wanting to return to Germany.
However, this link has a whiff of Sheffield Wednesday being the interested party and the agent dropping QPR to the press to drive a harder bargain.