Other than the lack of gym badges, and the fact that there are no new Pokemon, Collosseum and XD both feel a lot like a main series game to me. I am a huge fan of both games, it was nice to have a less happy, Dystopian Pokemon region, and the player character having a darker edge was really nice.
And the fact that the Game Cube games had a daycare, and you could trade back and forth with the main series games really helped to make the games feel main series. Unlike the other spin off games, which have little to no connectivety to the main series.
It is foreseeable that a "new region" (remember the Game Cube games were in the Orre Region) could be a Wii or Wii U game. It could be unlikely. But it is possible.
Gamefreak doesn't recognize the Gamecube games as main games, had nothing to really do with their production and do not count anything that happened within those games as canon to their universe. According to Gamefreak Orre doesn't exist (Pokemon traded from those two are Hoenn Pokemon or Faraway)
As for connectivity, all of the Ranger games CAN connect with the 4th Gen titles. You cannot trade between, but you can send Pokemon from the Ranger games to your main series games.
Stadium and Stadium 2, the forefathers of Colosseum series, could interact with the main games, trade with the main games, give you Pokemon into the Main Games, deposit the Pokemon and trade pokemon through it between the games. They interacted with the main games MORE than the Gamecube games did. PBR also has about as much connectivity as the Gamecube games did and so does Pokemon Ranch where you can trade Pokemon to the Mii in charge of it for Rare Pokemon. Spin offs have been able to connect with the Main series games.
Gamefreak themselves have stated that they will not make any main title game for the home consoles because the games are made specifically for the travel consoles. They are meant to be played as you move about easy access while you travel. They don't like the idea of making a home console main game and will continue to make the main series specifically for the handheld consoles.
I love the idea of new regions in X and Y. I mean, it's not unheard of to update games. I mean, they already dealt with the Lumiose City save glitch.
Also, more evidence for new regions is the Pokedex:
When you talk to Professor Sycamore about how many Poke'mon you've caught, he says something along the lines of
"You've caught XXX Poke'mon. And XXX of them were in the Kalos Region!"
As of right now, both those numbers are the same. I think this is pretty solid. Otherwise he would just say "You've caught such and such Poke'mon" The end. But no, he specifies.
Also, I'm not sure whether previous games had "Regional" Pokedexes, but I found it odd that the X/Y Pokedex is divided into Coastal, Mountain, and Central, and then a National. I see this as a huge implementation.
Third, the Cafes around Kalos, in which you pay to do absolutely nothing. They in fact DO have a purpose.
You pay to talk to people in the cafe', and when you talk to them, they show you their Poke'mon, which gives you a Pokedex entry. Today, I received an Entry for Entei. (Yaaaaayyy =3)
I haven't seen the strategy guide, but I don't think a strategy guide would put much emphasis on flavour. I think if a guide says something along those lines, they are intended to be factual.
These are a lot of really good points. The fact that they divided the region up made it interestingly important enough to imploy there might be more out there. Also I never caught that Sycamore said that so that's really hinting more might be coming rather quickly...
Sycamore says that because he'll be able to tell you how many Pokemon you have caught in your Pokedex are from Kanto, Johto, Hoenn, Sinnoh, Unova, and Kalos when the Pokemon Bank opens. When you transfer the Pokemon into the bank and withdraw them into your game, their original catch location data transfers with them. They had snippits about being from Johto or Kanto in their Pokemon bios when you looked up their basic information in your Pokemon's status screen.
So if I were to transfer my 5th Gen Pokemon, he'd tell me: I have caught XXX amount of Pokemon. XXX are from Kanto (I have a lot), XXX are from Johto, XXX are from Sinnoh, XXX are from Unova, and XXX are from Kalos. (I have yet to transfer from a Hoenn game and have almost a complete Hoenn pokedex yay~)
That's why he says it the way he says it.
I don't believe we'll get any new Region, unless its a replacement for Pokemon Z/X2/Y2 and gives us the Pokemon that were unavailable in X/Y in those copies and make some from X/Y unavailable in the new one.
Highly unlikely, but better chance than DLC which was stated to be non-existant for X and Y by Gamefreak already.
About the guides....No...a LOT of what's in guides are there just for fun. I had a LOT of useless information from a Prima Vista Strategy Guide for Chrono Cross before. They throw those in there the same reason a magazine writer uses their personal opinions in their excerpts on video games. One of them for X and Y was really unprofessional even though it had a lot of good things to say about X and Y. Guides are written by groups that aren't affiliated with the main company. The company only has to go through the guides to make sure that the main information is correct. The people who write them do so the same way we would write a guide. They play through it many times and catch as much detail in the game as they can. They don't get any privileged information from the main company so even with a comment about transferring berries from another region is in the guide, its quite possible that that was an opinionated oversight by the writer. They probably thought that you could transfer the berries over when the Bank opens.