I'd be perfectly fine with Orre replacing Hoenn, thank you very much.
Anyway, such a game will present problems, both in terms of cartridge space, and how levels would work. We have five regions. Pokemon can have up to 100 levels. 100 didived by 5 would mean that at most each region could vary levels by an average of 20, which is way too tight for my tastes.
And I would not be cool with starting over with a new team for each region. That kinda defeats the purpose of having them all in one game if you can't keep the same team for all of them.