I do not believe the theory of Dragoborn being a incarnation/Avatar of Lorkhan, i do believe he is Talos incarnate. But the Folks in Sovngarde mentioned Shor/Lorkhan is actually alive so he must be moving about somewhere and escaped death. So hes not the Moons anymore. I would love if the a later Dlc Focused on Lorkhan.
You don't believe the Dragonborn is an incarnation of Lorkhan, but you believe he's an incarnation of Talos? Talos IS Lorkhan.
Shor is most definitely not alive. He's the Dead God. That's why he's in Sovngarde. He also can't just not be the Moons anymore, that would mean he isn't himself anymore. Your argument might hold up if the Moons had vanished from the sky--which happened incidentally, it was called the Void Nights, and the details are obscure, but the Moons are back now.
Most games
and DLC are about Lorkhan in their own way. He's a behind-the-scenes god that is ultimately responsible for everything, along with Aka.