You said that Hoenn can't use the unused areas, but then turn around and say within the same paragraph that the point of leaving unused areas on the map would be for expansion.
How can they expand if they can't use the Unused areas that they purposefully left on the map for Expansion?
Also Hoenn's Map is zoomed further out if you read the posts instead of picking out of them. If they ZOOMED Hoenn's Map in there is ample space between locations, especially if they use B/W's style maps that show detail on them rather than topography.
As for the Sequel...Team Rocket in G/S wasn't "better" than Team Rocket from R/B/Y/G. In fact they were a small pathetic fragment.
And really you argue sensible logic over the already established Magic Logic Pokemon used TWICE. Palkia/Dialga were going to simply destroy the reality they were already in and create a new one. HOW is THAT more plausable than threatening to destroy a region through Flooding/Volcano to make a new region that much off base? And yes it actually is a bit more possible.
Islands that have civilizations destroyed through Tsunamis and Volcanic eruptions every few centuries. After a while the water recedes or the plant life regrows on its own and the Island become re-inhabited by people that find it only to have the cycle repeat itself later down the line until the Volcano dies. Its the same basis as what Magma/Aqua were trying to do, though they just sugar coated it, thinking it wouldn't be as destructive as it was. Yes it would be a rough Carbon Copy of the original Plasma, but then again, Team Rocket in G/S/C was a rough (albiet pathetic) Carbon Copy of Team Rocket from R/B/Y/G. Team Plasma from B/W is a Carbon Copy of Team Rocket, mixed with Team Galactic's ideas, under the disguise of Team Aqua/Magma.
Team Plasma wanted to become the Rulers of the world (Rocket/Ghetsis), N wanted to create a New World where Pokemon were free of Humans (Galactic's Recreate the World), and were doing so under the disguise that it was "good for the Pokemon" (Aqua/Magma's Logic for Expanding the Sea/Land).
Even in the Sequels all they did was recycle the same team with the same goals, using the same methods they did in the past. Why wouldn't that be possible in a Seequel for R/S? Its been done that way twice now, if a Sequel were to happen, then there is a good chance it'll happen again.