Talos, in terms of godhood, is nothing more than a replacement of Cyrodiil's highly watered down version of Shor, Shezarr. And no, Talos is not dragonborn, that was Tiber Septim. If anything, it'll likely be an aspect of Shor who appears. Perhaps, the PC, or not.
I was under the impression that Talos = Tiber Septim. I believe he achieved some level of godhood at his death. It's a similar situation to Roman leaders, which the empire is based off of, that were deified upon death and worshiped as pseudo-deities, like Augustus and Julius Caesar. In fact, the real world term for this is an Imperial Cult, the same term being applied to the religion of the Imperials in Elder Scrolls. Arkay, likewise, is said to have once been mortal, but was deified when he discovered the secrets of life and death. But the Monomyth contradicts that, so who knows? I have no idea if Tiber Septim is an actual divine entity or just an overglorified conqueror, but he has a place in both Cyrodillic and Nordic faith as Talos and Ysmir, respectively. I wouldn't call Talos/Ysmir a replacement for Shezarr/Shor, but Shezarr was filtered out of Imperial society due to racial tolerance for their new Elven citizens and a conflict of interest with the reverence of Akatosh, a god that dislikes Lorkhan.
I'm not very familiar with the Nord gods though, but it seems like they have the same number as the Imperials, 9, but they lack Arkay and have Shor. At least I think they lack Arkay. I didn't see him listed anywhere. Arkay, though, seems like more of a replacement to
Shor than anything else. Shor is the god of life, Arkay is the god of life and death. They serve similar purposes on appearance, despite the lore behind them being less black and white.