I really hope they keep the land:water ratio the same though. The story is about Kyogre and Groudon, so there should be similar amounts of land and water, I don't know why people complain about there being so much water, I think its great! I think the water routes can be incredibly versatile, and if they include things like coral reefs, etc like you suggest, I think we can get people off that mentality that water routes are boring!
Because the water routes we have
are incredibly boring. It's long straight of water connected to a long straight of water. There's dive spots, but those aren't varied enough and most require a second run through. Sometimes you'll get some shallow water.
I mean look at this
Look at how bland this is.
This is kind of better, we got like mangroove trees and some rocks, but it's still visually bland
And since they wanted an equal number of water routes, you have the ridiculousness that is routes 129-131, which is just one long straight stream of water routes. And there is NOTHING THERE except for the Sky Tower on 131. 130 is literally just a corridor and the first thing that comes to mind when I think "Hoenn Water Routes"
And in addition to that, a lot of the trainers are swimmers & fishermen who are invariably going to have the same bunch of water pokemon. *But* at least the shallows allow for breeders & ace trainers and so on.
The absolute worst thing that makes everything just come together and be all samey forever is the pokemon. Hoenn's got a lot of water types but they're spread out across 3 fishing rods, surfing and diving. So all you're going to find are Tentacool, Wingull and Pelipper. And I think all within the same level ranges.
All the pokemon games have this problem, but they hide it better by not having as many water routes