I've become reluctant to speculate because at the end of the day, Bethesda can go whatever route they feel like. I mean, who here expected House Redoran to not only recover from losing its Archmaster, losing the gods they put so much faith in, the destruction of Ald'ruhn (and the closely related line from MK- REMEMBER REDORAN. NEVER FORGET.), Red Year, and the Argonian invasion, but also become the most powerful Great House in Morrowind?

They did have something going for them with the Argonian invasion. They're far to the north so the Argonian forces would have needed to get through the Dres and Hlaalu territory at a minimum and in TES3 they didn't seem to use slaves as much as the other houses, which would make them less of a priority. Besides, most powerful House or not, what's left of the province seems to be hanging by a thread.

Martin's sacrifice closed the Liminal Bridges and ended as well as fulfilled Alessia's covenant.

There is no need for the Dragonfires anymore.

There was the curious manifestation above the city of Cyrodiil, during the Stormcrown Interregnum. A physical Stormcrown, if you read the account. Talos still has a say.

Where is this account?

http://www.uesp.net/wiki/Skyrim:Rising_Threat,_Vol._IV. I don't know if Talos was behind it, but if there is any truth to the account, there was definitely some metaphysical stuff going on during the Stormcrown Interregnum.

Well hey, they could have chosen any number of strange things, or nothing at all, because the novels never talked about it, but the writers for Skyrim took some creative liberty punctuated the Stormcrown Interregnum with a literal storm-crown. A wizard could have done it, but I'm pretty sure the reader's supposed to get a clue. Just my 2 cents.

What if the septim blood line had not died but had gone into hiding because of the idea of too much pride or maybe they had something to dread