I wouldn't mind it at all, as long as you don't have to normally fight it off like some goddamn plague. I want my people to be reasonably loyal, with the chance to make them both overzelously devoted or backstabbingly hangable.
I think that cities will be a very major thing in Elemental, though. I somewhat doubt there'll be something like this in the game, barring a major event, for that reason. Loosing or gaining a city will probably be a fairly major thing, able to decisively change the ongoing situation.
But I wouldn't mind it, as long as it's fairly rare, not too hard to work against, and is a huge 'thing'. And if it happens, I want the option of going there, and having the citizenry devoured by my bears.