I have a feeling that the next Chapter is going to be something very different... something that we may not even call a Chapter, but a sequel to the trilogy. Guild Wars 2.
Why do I think this? Because I can't see any more links in the current game world to major lands outside of our maps that could be used for new PvE campaigns. Cantha was a fairly obvious one and was predicted early on. After that people quickly looked to the Elonians and the Margonites who had come to the Crystal Desert as the next link - that we'd visit their homeland to the south/east of the desert. And now we have it.
There are things such as the druids of the jungle, the Charr homelands, and the Mursaat 'city'... and even unknown invaders who came across the sea to the Watchtower Coast long ago. But these cannot form a whole new stand-alone chapter in my mind.
The next Chapter is a new beginning after the end of this trilogy and so I believe we may return to the old continents, some years on in game time. There may be new foes invading, or a new destructive force bringing its foot down on Tyria, Cantha and Elona. We may return to see things such as a green, revived Ascalon, Deldrimor victorious in the Shiverpeaks, the White Mantle crushed in Kryta and the old monarchy restored, a new safe path between the Crystal Desert and Elona, new god realms (Dwayna, Lyssa, Melandru) opened up, and the Charr being driven back to the northern lands they came from. And of course in Cantha there may be new trouble afoot between the Luxons and the Kurzicks, or a rebellion against the emperor driven by some evil force. All of these are speculations but there is so much in the old continents that can be refreshed, changed, expanded upon and added to. There are plenty of gaps in Cantha and Tyria that could be filled with new explorable areas and missions against new enemies.
And you never know - with all this they could even refresh the battered old PvP realm, not just with things like new Guild Halls and skills. Plus they haven't given us an improved trading system or better storage or... nah I'll stop there
What I'm saying to the OP is, if one of the teams goes back and reforms the old continents - better to do it all together and make a shining new chapter filled with new content and features. In fact, they may already be doing so.