To the victors go the spoils, and I have little doubt that status quo ante bellum, at the very least, would have been one of those conditions.
But which side was the victor?
What the Alphans achieved was comparable to the Nazi victory at Dieppe: they beat back (barely!) an isolated beachhead force, without managing to inflict any damage on the main forces or the industrial base of the enemy itself. And the very fact that the beachhead force was so formidable, so self-sustaining, so immensely capable industrially, hints that the "mainland" Dominion would be an impossibly strong opponent for the Alpha players. It wouldn't matter a bit if every Dominion "mainland" warship was sent to the beachhead force and perished there (or was forced to be scuttled ior handed over at the conclusion of the war - something that was never even hinted at in the final episode), because the industrial base demonstrated by the Dominion could whip up ten thousand ships more basically overnight.
In addition, as the Dominion had been the obvious aggressor, such gave the Alliance leverage to demand their own listening posts in the Gamma Quadrant as a precautionary measure.
It might be that the Dominion would agree to be labeled aggressor. However, if they felt like not doing it, they could just as well state that the Federation had performed all the aggressions, and that the Dominion response had been reactive rather than proactive. After all, Alphans had trespassed on Dominion territory, not vice versa. Alphans had squatted on Dominion land, not vice versa. Alphans had performed a mutually agreed
casus belli in mining shut the wormhole, as response to theoretically nonaggressive Dominion actions of maintaining peaceful traffic with their Alpha ally. The Jem'Hadar had responded in force to these blatant aggressions when required. And while some insidious attacks had been carried out against Alpha, those couldn't really be nailed on the Dominion... Indeed, everything would suggest that at least one such episode was framed on the Dominion by Alpha schemers, namely the bombing in "Homefront".
The Alpha side could prosecute. But they would have to tread
very softly, lest the accused wipe out the court.
There's sufficient reason to speculate that the Founders' impending deaths had weakened the political infrastructure.
Possible, but a bit unlikely, considering that the Founders weren't part of that infrastructure. The Dominion is not the kingdom of the Founders: as described, it is a front behind which the Founders can anonymously hide. The Dominion runs itself, and isn't even aware of the existence of the Founders.
The scheming Vorta might become a destabilizing element if they knew the Founders were dying. But one would assume the scheming Vorta would
always have been a destabilizing element. The structure of the Dominion would have to take that into account. And we know the Vorta basically live in mortal fear of their Jem'Hadar underlings, in a complex but fairly robust setup that reminds me of a certain Jeff Hawke comic... This would be a good mechanism for limiting the reach of the Vorta, who in practice run the Dominion anyway, Founders or no Founders, and thus shouldn't get unduly excited even if there was a prospect of the Founders dying out.
A general insurrection as a result of seeing the Founders' communal weakness and having lost a war for the first time in the Dominion's history is not outside the realm of possibility.
"General" in the sense of "within the small cabal that knows about the Founders in the first place" might happen. But that would only include the Vorta and the Jem'Hadar (plus possible other, so far unknown subject species engineered to greater or lesser degree), and while the Vorta are pragmatic bastards, we have little indication that the Jem'Hadar devotion to their gods would be subject to vagaries of secular fate.
A more likely scenario would be secular Dominion unrest as the result of a temporary weakening of Jem'Hadar forces. But the Jem'Hadar aren't constantly present. It is the threat of their sudden appearance that keeps the Dominion at bay, not their constant presence. Indeed, the personal cloaks of the Jem'Hadar warriors are a perfect way to enforce the "Are they here? Do I dare act, or even speak?" mentality of constant fear... So the sudden absence of the Jem'Hadar would not actually differ from status quo in any noticeable way.
The Founders would seem to have all their bases covered. It probably isn't a coincidence that their Dominion has endured for ten thousand years. Or at least they have managed to drive home the propaganda that this is how stable the system is, which amounts to pretty much the same thing!
I don't think "What You Leave Behind" was much more of a victory for the Alphans than the one the injuns had over Custer. The terms of the peace would be entirely dependent on Founder goodwill - and both sides really should settle for terms that minimize the chance of further bloodshed and undo the original causes of the war. Effectively closing down the wormhole (within the limits set by the almighty Prophets, of course) would be a more acceptable solution to both sides than persisting with the solely Alphan idea that traffic through it should be allowed.
Timo Saloniemi