One of the recurring rumors in the MMO blogosphere is that World of Warcraft would come out in a version for this or that next generation console. With variations of the rumor being either the console game accessing the same servers as the PC version, or there being a "lite" version for the console, not requiring any keyboard. I don't know if Blizzard will ever do that, but there is already a lite version of Everquest called Everquest Online Adventures for the PS2, and Final Fantasy XI has both the console and the PC access the same server. With the next generation consoles being increasingly networked and internet-ready, it is only a question of time when we will see more console MMORPGs.
One of the recurring comments in the MMO blogosphere is console gamers wouldn't be very welcome, being not as "mature" as PC MMORPG players. While it is true that the average age of a console gamer is probably much younger than the average WoW player, and that the monthly fee keeps a lot of bored teenies away from MMORPGs, I don't think that expanding the MMORPG genre to consoles would be a bad idea. In fact the growth in total player numbers would probably allow us to split the genre is several sub-genres, appealing to different demographics.
There are already existing differences in MMORPGs: PvP vs. PvE-centric. Casual vs. hardcore. World-centric vs. game-centric. Soloable vs. enforced grouping. But in most cases these are just differences by degrees. The PvE game LotRO has a PvP monster play part, while even the most PvP-centric game like Lineage has PvE parts as well. Nobody agrees what a casual game is, even WoW is too hardcore for some. Nearly all games offer both solo and group content to varying degrees.
Where I see a much clearer split of the genre coming is in the way that MMORPG combat is handled. Several of the upcoming games are promising to make MMORPG combat more action-oriented, with aiming and more frenetic clicking. Apart from the technological problem of how to realize this when there is lag, MMORPG action combat obviously would appeal more to a younger demographic. Older players, like me, aren't really excited about the idea. Me, on the other hand, I'm dreaming about MMORPG combat which would be more strategic, slower, and require more thinking. I get excited about games like Puzzle Quest and Metal Gear Acid, which use puzzles or trading cards as combat mechanism. But I'm fully aware that this deeper but slower way of combat isn't likely to attract the younger crowd. But hey, if the genre grows big enough, there is room for games for all ages. Even a turn-based strategy game like Heroes of Might & Magic 5 still sells very well, because there are enough older gamers out there to buy it.
Consoles would be ideal to support action MMORPGs, with or without sharing servers with PC clients. The MMORPGs with slower, more strategic combat mechanisms would probably sell better on PCs. Besides the differences in combat, console MMORPGs would probably be more game-centric, with few social elements. It's hard to chat using console controls. On the PC side games could become more world-centric compared to WoW. The recent article on WoW in The Times discussed among other things how the (adult and female) author would have liked more social elements in the game, for example having a jukebox and a pub quiz or raffle on offer in the WoW taverns.
On the business model side, games with no monthly fee would probably be more attractive for a younger crowd. For older gamers a monthly fee isn't that much of a problem, and many would even be willing to pay more for things inside the game. That could be booster packs for the trading card combat game, or it could be fancy outfits like those being sold in Second Life or some Korean games.
In short, there are lots of ways in which MMORPGs could develop, and they aren't all going to be of the one-size-fits-all kind. By accepting that different solutions of platform, combat system, or business model could be ideal for different demographics, the genre could open itself up for a much larger variety.