In Morrowind lore it is said that the Dwarves mysteriously disappeared during the Battle at the Red Mountain; ring a bell?

Upon destroying the Heart of Lorkhan, Dagoth Ur becomes mortal. When you 'Beat' Dagoth Ur after the heart is destroyed, you don't actually see his corpse, it disappears! What happened to it though? When the Dwarves disappeared, where did they go? You could say Dagoth Ur is alive, or you could say he's dead. Although, a small bit of evidence says that he is still alive.

Remember before you even entered Akulukhan's chamber? In the facility cavern where you first met Dagoth Ur? Well, when defeating him there he also disappears and the door to the chamber opens! When you enter the chamber, Dagoth Ur is in there. So doesn't that just mean Dagoth Ur was transported somewhere else? Maybe even to the Dwarves whereabouts?

I've never found anybody who even considered that he might still be alive! I hope this changes that.

Anyway, what do you think about all this?

Not likely.

Essentially, Dagoth's lifespan was largely tied to the Heart of Lorkhan. So long as it was still around, he couldn't die. Now that it's destroyed, he's mortal, and would likely have died had he actually survived the heart's destruction. Being locked in an airless void without sustinance of any kind will do that to a mortal or semi-immortal being. Note that Corpus protects from age and disease; it says nothing about air, food, and water.

Also, the Dwarves became the golden skin of the Numidium. While there's no definite proof in-game that this has happened, it's pieced together throughout extra-game lore, what's been told in Morrowind, and even by Dev commentary. It's a fact in all but name, effectively. If Dagoth went the way of the Dwarves, his body fused with Akulakhan, which was destroyed once the Heart of Lorkhan had been destroyed. That DEFANTLY would kill off Dagoth Ur.

Anyway... even in the extremely unlikely event that he was sent to some far plane, he's effectively out of TES forever. He'd be beyond Atherius and Oblivion, where not even the Aedra, Daedra, or Elder Scrolls can reach. I'd put his chances of coming back about the same as TES suddenly turning into a Call of Duty clone.