I think I would like to see Calvert show up just before the depart and perhaps with the privateer Vulture under his command. Then they could send Humphries in THAT ship and allow Granger's to remain. And if all the previous officers are dead or about to be hanged, perhaps with Maidstone then life would be so much better for everyone.
I am concerned that the news of Granger's condition may cause severe repercussions in England. The King will feel awful because he hand picked Granger for this mission. Sure, people are commanded into battle in his name often, but he hand picked this man himself, and that gives him a face and a name. So he may see some huge elevation in his rank, status and peerage when he gets back. And the Prince of Wales may already be working to see that his family is taken care of. Even if he is still alive.
A twist would be for his death to be assumed and for the Duke to take Caroline for his wife since she is carrying his child. Thus insuring that both, Granger's family AND the Royal bastard would be taken care of. And if the child is born AFTER they marry then he would not be a bastard. But Mark never throws us curve balls does he. (Notice the lack of a question mark.) (lol) The twist would allow Granger to be alone with Calvert sailing around all over the Mediterranean for the rest of their days. Who knows what twisted plot Lord Arbour will hatch. Just know that it is bound to be twisted tighter than sisal rope and never what we expect.