I can't see them writing out Morgan, simply because he's Carson's son. But they could recast him. I can't really see them getting rid of Britt or Nik, either. Not because of Brik, but because of the major Cassadine story that's rumored to be about to play out. I would think that Britt/Nik would be a huge part of that. Especially Nik, if spumors are true and Stravros is on his way back. Liz is the only character of the four mentioned that I can see as a victim of collateral damage. But like I said, they may not want to risk outright firing her again. Who knows.