That’s just it - Martin hasn’t finished the books, so there is currently no end to the story..aside from what the show writers come up with.
Martin has apparently given them an outline of how things end..but has also said that aside from the overall gist that story arcs for “secondary characters” (which could include pretty much anyone aside from Daenerys, Jon and Cersei) are likely to be much different when..err..IF..he finishes the books.
I think Bronn winds up on the throne. Longshot but something tells me it’s quite possible