So, according to Lore, the god Talos is all that's holding the world together? This does not sit well with me for several reasons, which I'll elaborate:
1. In some texts, it's implied that Talos is preventing the kalpa from restarting (somehow). Yet what isn't explained is why he's prolonging the kalpa. Why not, as the Greybeards say, let the world be reborn?
2. The Thalmor....now can you really be sure that their anti-Talos crusade is really for the purpose of "unmaking" the world when everything in-game points to them seeking dominion over Tamriel? It would make more sense that the Talos persecution is linked to Numidium and the siege of Alinor, since Talos only became a god thanks to the Warp of the West. And I don't recall any Thalmor agents mentioning a return to the Dawn Era.
3. And finally, let's assume that it is true and Talos is the cosmic keystone keeping the world intact. This brings up a very pressing question: Why the hell is Tiber Septim getting this Mary Sue treatment? It was bad enough that Oblivion practically painted the Septim dynasty as a line of Emperor Mary Sues who are the chosen ones keeping the world from being invaded by demons. Making the fate of the world hinge on the worship of Talos is not exactly an improvement over that level of bull****. And ever since I played Morrowind, I always interpreted Talos as being no different than Vivec, Almalexia, Sotha Sil, or Dagoth Ur.....just a ruler who achieved apotheosis.
1. Yes we don't know his reasons, but that doesn't mean his reasons aren't good. If I had to guess why he's trying to stop it I'd say it's for the reason that any of us would. He cares about the people who live on Mundus and he doesn't want to see them die and suffer if they don't have to.
2. I think unmaking the world, or at the very least freeing their people from it, is a very long term. Right now they just want to rule over the mainland. Oh and the ban on Talos worship is probably more about creating unrest in Skyrim than anything else.
3. Talos, or the people that make him up, were all aspects of Lorkhan and he is the very spirit of Nirn, so I suppose if you could kill him or at least get his divine spark out of mundas then it might become unstable.
With that said even Trinimac and Auri-El couldn't kill him, so I don't know how anyone else would go about doing it...