Dennis,
What happens to the buildings that are normally destroyed during a city conquest, with the new tourism reductions to unrest time and population loss? Hopefully the percentage of buildings lost is also reduced with increasing tourism influence?
My concern with the change is that having high tourism could actually make a domination victory harder, because conquered cities would cause more unhappiness than they otherwise would. If conquered cities ALSO lose their colosseums and such, that would make the happiness even harder to deal with. Furthermore, having high tourism would also mean that it takes longer to raze a city. It's still generally nice to conquer a functional city, especially when it's a capital, but I might potentially have to think twice about building up my tourism if I'm going domination, and that seems weird to me. It's hard to say without play-testing it how that dynamic would work, but I thought it was worth considering.