Feeling a bit better I changed my mind and had a go today. The legal position is that by the provisions of the 1529 Treaty of Grimnitz the heir on the extinction of the Griffin line, which occurred with the death in 1637 of the last Duke, Bogislaw XIV, was the Elector of Brandenburg. At the time this was Georg Wilhelm, father of the Great Elector and grandfather of the first King, Friedrich I. Georg Wilhelm’s lawful heir today is of course Georg Friedrich, Prince of Prussia, so he is your answer.
I presume however that you wanted an answer based on the principles of hereditary succession. This would not be the heir by male-preference primogeniture, a system never used by any Imperial fief (which Pomerania was), but either the Salic or semi-Salic heir. Pomerania was pure Salic, but if it had operated semi-Salic law then I believe the answer would be Christoph, Prince of Schleswig-Holstein.
Bogislaw XIV’s great-great-grandfather Bogislaw X, the Great, who reigned 1474-1523, was like Bogislaw XIV sole Duke, other lines having died out. The Duchy was again partitioned between his two sons, but descent survives at all only from the elder of these, Jerzy (George), Duke of Pommern-Wolgast. He also had two sons, but the elder died young and the posterity of the younger, which included Bogislaw XIV, is entirely extinct. So we need to look at the male line from the eldest daughter with issue. There were two daughters also, each of whom had but one child, a daughter. OK, the male line from the daughter of the elder sister then.
This was Elisabeth, daughter of Anna Margarete of Pommern-Wolgast by her husband Ernst, Duke of Brunswick-Grubenhagen. She married Johann, Duke of Sonderburg-Plon, and not only had sons but has a surviving male line today, the senior of which is the aforementioned Prince Christoph. Here is a male-line only descendancy from Elisabeth of Brunswick-Grubenhagen. It goes to the maximum 12 generations, so you need only look down it to see the first name in that 12th generation. This is Hans, eldest son of Friedrich, Duke of Schleswig-Holstein-Sonderburg-Glücksburg, but he was childless and the next brother Wilhelm died aged only five.
That left a third brother, Peter, who succeeded as Duke and when he died was succeeded by the present Duke, Christoph, who prefers to be known as Prince. All this can be seen in the descendancy here from Duke Friedrich. I don’t think it means anything, and I would regard the legal heir as the Prince of Prussia rather than Prince Christoph, but the latter is I believe the heir by semi-Salic law had that applied to Pomerania.
As it happens, though this means even less, discounting morganatic lines the heir by male-preference primogeniture could be argued to be that very Prince of Prussia. If you go back to the descendancy from Elisabeth of Brunswick-Grubenhagen, you can see that until his death in 1921 the senior male from her was Ernst Günther, Duke of Schleswig-Holstein-Sonderburg-Augustenburg (generation 10), but he was childless, as can be seen from this descendancy from his father Duke Friedrich of the same. His eldest sister was none other than the Empress Augusta, first wife of the German Emperor Wilhelm II and mother of all his children, and Georg Friedrich, Prince of Prussia, is of course the legal heir of Wilhelm II and thus the Empress.
Anyway, I hope the above was what you wanted. I have tried to answer the question in two different ways, or you could say two and a half, and maybe one of the answers will content you. It was an interesting little project, and if anyone else has questions like this I am happy to answer them too, though I would prefer them to be posed in the discussion thread at the top of the page rather than in a separate thread like this. Any member can start a thread in this section and is welcome to, but if they start proliferating I reserve the right to move all posts to the discussion thread, thus effectively deleting the separate thread and avoiding the section getting cluttered. Don’t be put off, this isn’t a threat and I very much welcome others’ participation in the section, but I do like to keep it looking tidy too.