Maybe there will be a cutscene where he uses all guardians classes supers at once and goes down in a blaze of glory by non stop self resing nova bombing storm trancing dropping weapons of light while fist of havocing while holding a hammer of sol and shooting shadow shots and getting that extra damage with golden gun and then finishing them off with arc blade

We don't know, I think Bungie did the same thing they did with the Queen in TTK. I think he's still alive, but captured by Garry. It would make sense if they put that in place of Rasputin on the Dreadnaught in one of the first versions of Destiny's story