I don't see them lumping all the regions together just yet, maybe two (Start in Hoenn, go to Sinnoh(?)) but that's it really,
You could travel to Johto and Kanto which would be much closer than Sinnoh from Hoenn unless you took a plane.
I don't think Gamefreak wants to do one massive game. They've put it off and even told fans that they had no intent on making one, when it was brought up as a home game issue. Even if the storage capacity is higher they'd probably have to sacrifice a lot to be able to fit more than 2 region into the game carts. Given that there is a lot of codin that has to go along with the region itself.
Tiles change with time and weather, individual grass movement, music, Pokemon spawns, and individual region events, not to mention they'd have to start adding in a lot of new information to make up for the lack of story for each region and have to give everyone a valid reason to attend each region.
By the time you are through half of the third region, you also have a high chance of being level 100, which leaves the 4th and 5th region with nothing but level 100s which isn't very appealing to everyone.
You also have gamefreak's signature reason for making games to consider. We'd get 2 games missing a lot of Pokemon from one game to keep connectivity between the two games. Gamefreak will pull out a lot of pokemon to force players to trade between games and that could become an unappealing part of the game itself.
There is too much to think about when it comes to merging all the regions into one that in the end its too much work for little possible prize.
Home Consol, MMO, Mash up of the regions is an idea that all fans have had in the past, but its an idea with a lot of potential to kill the franchise only in the it gets harder to update department because if they release a new region they have to re-release the master game with all the new Pokemon, attacks, items, character, music, events (or even more new events).
Too much hassle, not enough positive feedback on it.
I'm down for accepting a remake because its what we pretty much expect. I think Gamefreak even expects us to continue with the "Oh when we getting x Remake?" Its going to be the same for D/P/Pt when the next console comes out and reveals that it isn't compatible with Generation 4 or 5 titles cause it won't play DS carts.
As soon as the next big thing comes out we'll move to the next game down the line. That is unless Gamefreak does the unprecedented and goes with another new Generation before Remakes.