Cardassians would be stripped of the majority of their territory. Certainly any "colonies" with indigenous populations would be evacuated of the resident Cardassians, and should the natives be primitive, Cardassian technology and structures would be removed. Any star systems/planets in previously disputed areas would be transferred to non-Cardassian parties. Chakotay's people would finally get their planet back, others too. There would be legitimate need for the Cardassians to retain small patrol starships, but their medium and heavy warships would be confiscated. Colonies established on uninhabited world might remain the territory of the Cardassians.
I know I'm necroposting, but...boy, do I disagree. This is exactly the kind of policy that France and the other allies (minus the Americans) inflicted on Germany after 1918.
Kind of backfired, as stripping a proud nation of its territories and technology made the ascent of people like Hitler possible in the first place.
Do this to the Cardies, and it will end up biting you in the arse, even if it is a few decades later.