In his defense, "I like it more," is generally not considered a compelling argument for something's canonicity.
I like RPGs more than racing games and I like TES more than Halo. None of this is real, so in the end, "I like it more" is all that we have. I am also confident that most educated people will agree that the material written by Michael Kirkbride exhibits, generally speaking, a superior command of the English language and a deeper view of the fantasy genre while conveying a more complex message.
The Covenant, symbolized by the Amulet of Kings, was broken in that very instant the Amulet was shattered. No longer do we have a Nine-sanctioned Empire, with a divine right to rulership over Tamriel, to protect the Mundus any longer. This didn't matter during the Interregnum between Alessia and Reman, or Reman and the Septims, because other Towers stood. It matters now.
The Covenant, yes. The Oversoul of Emperors and the spiritual lineage of Alessia is gone.
It could be said that the statue of Akatosh, which is a new symbol of something that nobody in Tamriel seems to quite understand yet, is a Tower in and of itself now. But what binds it? Certainly not an agreement to maintain an Empire that promotes the worship of the Nine (And remember, belief is power). That Empire collapses a short time after the Oblivion crisis, as evidenced in the Infernal City. That Covenant no longer exists; or can exist. There is no bargain.
Whatever it is, and whatever Oblivion neglected to explain it to be, it keeps the Daedra out. It is pretty clearly an agreement between Akatosh and Martin, or at least a reward for his faith and sacrifice. It looks like a bargain to me, a new Covenant. It's just not one that comes with refills, privileging a certain dynasty. But at least we still have Akatosh's favor and the intent to preserve the world. The terms of the contract have been renegotiated, but this has implications for the Empire and Cyrodiil rather than all reality, I think.
So what, do you ask, maintains the status quo until events align? Akatosh and his goodwill alone, bound by no agreement to mortals.
It's not like Akatosh was strictly obligated before, and I don't think he has changed his mind about Nirn and his continued existence being a good thing. He's an Aedra, not a capricious Daedra, and rather predictable. I wouldn't characterize his mind as something ineffable and superior. Try insane and sub-human.
And with, now that events have aligned, Alduin the World Eater, an aspect of himself returning to make things as they once were; in a way that, pre-breaking-of-the-Covenant, shouldn't be possible, it would seem that goodwill has run out.
I very much doubt that. The player character is made Dragonborn. Somebody up there still likes us. And I say it is still to early to call what allows Alduin's return, if anything does at all.