If, like Sergio, or Dave, or Vinny he was a worthy player who gave his all for our club and was a great ambassador over time, or just didn't fit in and was being asked to leave, then I'd wish him good luck in his new venture.
However, he's not, he's barely been here, been given ample opportunity, he's only young and he has chosen his path to leave and may come back to bite us one day if he does develop into a top notch striker, so I don't see why we should be thanking him, his massive wage packet should have been enough, nor would I wish him luck for his future career, especially if he comes up against us again.