I've really enjoyed this thread, and thought there were a good bunch of ideas in here. I'm surprised though that nobody suspects, like I do, what the next Trilogy (or the one after it) will be about
:
THE PAST.
It's been done so many times, and for good reason: it's relatively easy. The lands are already in place, much of the story is already figured out (since at the end, it has to line up with its known future), and there's no need to introduce new professions or skills. Of course, something would need to be new and fresh... how about races? Dwarves.. Centaurs... Elves?

Of course, in order for a player to pass between "past" and "present" worlds, they would have to be made to believe that the one in the "past" is the great-grandparent of the one in the "present" (except Elves, who are known for their longevity), because there needs to be some reason why essentially the same "person" with the same name and same skillset would exist in both time frames, without having to introduce time travel -- though time travel could be cool too; when magic exists, anything is possible, and someone could've introduced ruptures in time that provide consistent links between some kind of "before" and "after". This would work better if the trilogy in question is in the
FUTURE rather than the past, just.. because.

But anyways, let me get back to more serious responses to the things discussed above....
I have to say that really really dislike the idea of mini-expansion packs that aren't whole new Chapter releases. I think the current model is an excitingly innovative one. Ordinary game expansion packs are cruel, in my opinion, because there is always the suspicion that the content was left out of the original release just to get more money out of the players.. or even worse, the content is so tempting that the players feel they HAVE to get it in order to continue enjoying the game. I much prefer the idea that the new chapters are big enough to be treated as whole new games, even though I will be continuing to play my characters in the much larger interconnected world. I'm just glad that I don't have to get the next chapter until I'm ready to experience it. I'm very glad that I don't have to get Factions in a hurry just because I really want Material Storage, and I'm grateful to the developers for deciding to make it available in all chapters -- and I hope they do something similar with any other new features that can be added so easily to existing chapters.
The worst part about the idea for mini-expansions is the suggestion that they could contain new professions. I am amazed that Anet has done so well with adding new professions without disrupting balance, because of my prior experience as a programmer at an oldschool multiplayer text-based game -- balance is one of the toughest things to make work, especially when adding new skills or professions. Kudos to them for doing so well!! (I wholly support the skill balance revisions, also from my experience doing the same thing. Balance is tricky, and I'm betting it's possible for players to contribute to it by carefully explaining their situations to the developers instead of just crying "nerf!" when some change is not to their liking.) But above all else, the "new professions" in the new Chapters makes sense the way it is, because these new professions actually come from the new lands (this makes sense to me for all except Assassin, I must admit, though I suppose the notion that there are no Assassin trainers in Ascalon explains it well enough).
If people feel that the older chapters could benefit from cosmetic upheaval, like lipsyncing and whatnot, it could be called a Special Edition (or is that name already taken?) and it could replace the original edition on the shelves so new players get to enjoy the wonderful game experience, without feeling like they're buying an "old game". Any new
content should be made available in both the Original and Special editions, and it wouldn't be done at a loss because the Special editions would still be bringing in profit. Then players of the old version would not miss out on content, just eye candy, unless they wanted to upgrade to Special edition. I can see it now: "For a special low-low price of $19.99, upgrade Original to Special edition and get two more character slots!"

The game is still amazing, and with proper care it could continue to draw new players in and thus keep the towns brimming with excitement and potential groupmates.
I really love Guild Wars for all that it is, and all that it isn't. I don't think they'll need to do a total upheaval in order for future chapters to stay popular, except to keep up with the latest graphics capabilities. I love how small changes can be added to all chapters as they become available, and am looking forward to things like the extra storage (even if it's just more storage upgrades), and improved ways to advertise items to buy/sell/trade with other players (i've gotta go find a thread that discusses ideas for this! I have way more than two cents to contribute!)
And lastly, I have to agree with the person who said they hoped they'd still be playing GW at age 87!

See you in 2065!!