>>15601 (OP)
>What if the Dominion won the war?
Nearly happened, but it would have taken years more. The founding member worlds of the Federation all burn, Qonos and other worlds for the Klingons, and the Romulans lose many worlds along their borderlands of the Alpha quadrant.
Cardassians nearly extinct, if not extinct, and the other Alpha Quadrant allies of the Dominion end up grinding themselves to weakness during the 2nd advance into allied territory, all while Vorta-led Jemhadar forces just grow larger and more powerful in absolute and relative terms.
The Breen and any other allies find themselves forced into subservience, either by sense or force.
All other powers in the Alpha Quadrant, including the Ferenghi, Tzenkethi, and various other powers are all subjugated. Then, with no organizaed opposition left, ships are sent out to thousands upon thousands of world with terms of surrender.
Reasonable terms, just taxes and disarmament. Then the Dominion forces spend time absorbing it all, a decade, and then start working on expanding towards the Gamma Quadrant to link up with the original Dominion.
>No Borg
The Delta Quadrant looks completely different.
>What if OFFICIAL first contact occurs earlier before that crew of Vulcans found Cochrane?
Could have happened with Vulcans, Ferenghi, Vossk' people(kidding), or maybe Romulans? Klingons were pretty close.