Even if Vvardenfell was completely cleared of all life from the eruption, the close vicinity to the mainland would allow the nearby creatures and plants to regrow back in vvardenfell creating a simular yet different recreation of the previous landscape. The mainland plants would survive because they have survived many ashstorms and can endure the ash falling over the ground. The cities would be buried underground and new ones would be in their place. The dwemer ruins would be buried even further with more areas caved in especially right after the ministry of truth fell. But the availability of Ebony would bring people back seeing an opportunity in trade. Dunmer looking to restore their homeland would return as well. The argonians would claim some of the southern mainland and some houses would live on. Solstheim would be the easist but most boring to make and play in, as it has most of what is in skyrim already: More nordic tombs with draugr, horkers, and a lot of snow. And if that becomes boring, than the rest of morrowind shouldn't be barren or else it will be boring also. We might want to create a new post though once we start making progress and post screenshots, although until the creation kit comes out we can only plan and debate lore.