Fine points Paradox - I had ignored Dren especially - but those two are both Hlaalu - so infighting if they see the possibilities, but would they split their House?
Dren especially proved a solid Imperial Ally. But there is no more Emperor so I suspect if Ocato is not looking for or to be an Altmer Emperor and supported Helseth ...
Barenziah has another child - she is not Queen of Summerset Isle ... One family with 3 key Provinces.
It might spell an end to human hegemony and a new dawn for mer-kind.
since the Dragon Break it seems that it may have been that daughter of Barenziah who offered her firstborn to the Wormking ... so that's an interesting addition to the mix.
The daughter seems content with Summerset - so that would still leave Helseth in the driving seat provided Altmer King is agreeable.
Assumin that's the way of things then what remains is Hammerfell (in a few thousand years they may unify?); Elsweyr ... have never shown Imperial ambition; The unknown at the heart of the Black Marshes; the Nords who keep invading everyone and therefore would be resisted from several directions; the Orcs who do not appear to be ready for Imperial ambition though they enjoy the odd rampage; and Valenwood - it may be that they would not need to mantle a god if the Precursor is correct about the return of Yffre. But i suspect that if Valenwood changes course it would be to withdraw from any Imperial involvement.
The Earls, Counts and relatives of the former Imperial House do not count at this stage - they were totally ineffective vs Dagon's invasion as were the legions ...
1) Nords vs Morrowind, Summerset and Bretony - Mer Imperium Est;
2) Nords vs Morrowind and Summerset vs Bretony - Mer Imperium or chaos;
3) Nords vs Morrowind, Bretony vs Summerset - Mer Imperium or Human (likely mer) or chaos;
4) Nords vs Morrowind vs Summerset vs Bretony - total chaos or stagnation with Occato remaining as Cancellor;
5) If Occato is able to make the necessary deals to take the mantle and proves popular then the Imperium survives - but it will be very shaky.
One last thought - should Helseth marry an appropriate Cyrodillian heiress? That might change things.
Barenziah for Empress anyone?