Tying cardassia's fate on whether it was carved up/occupied by the victors or not is credible.
But, as regards the klingons and romulans:
As for the other POV, that of the victors... Klingons probably wouldn't be all that hot about weakening their enemy beyond a certain point. They prefer strong opponents, especially when those have been decisively defeated (compare to the idolization of Rommel or Napoleon in the British tradition). From which it follows that Romulans would love to give Klingons exactly what they want! And the UFP would want to see Cardassia rise again for humanitarian reasons. With such agendas at play, it is far from implausible that everybody would get way more than they bargained for.
Both klingons and romulans have empires. They use conquered territory for resources, and, when the native population is 'ready', for manpower.
The klingon/romulan conquered cardassian territory would be just that - conquered, under the conqueror's boot. No glorious freedom fighter defeating Godzilla with a paper cutter.
The notion that klingons would want to keep cardassians strong for, essentially, sport, would come at the cost of making the klingons a copy-cat of a really stupid bond villain.
The idolization of Rommel or Napoleon had no relevance on keeping Germany or France strong; if this happened, it was for completely different reasons (that actually made sense, pragmatically).
The romulans wanting to resurrect an enemy - their enemy - just so they can annoy the klingons, would come at the same price of making the romulans idiotic cardboard characters.
One would rightly wonder how did the klingons or romulans ever managed to create an empire with such thinking.
The federation could try to make their portion of cardassian territory 'free' for humanitarian reasons.
And, in the process, incur heavy protests from the klingons and romulans - who would be opposed to the existence of so relatively strong a cardassian state.
Potential for conflict abounds.