My two characters are only level 14 and level 4 so far, so running out of content won't be a problem for months. But I did notice a good article by the devs on endgame today:
https://www.guildwars2.com/en/news/the-endgame-reimagined/They also mention they're working on a lot of new events for that section of the game:
The launch of Guild Wars 2 is just the start. With the game now out in the hands of the players, we can focus our efforts to adding new types of events, new dungeons, new bosses, new rewards, and new places for players to explore. Together, our journey is just now beginning, and I hope to see you in-game.
Could be just BS, but it'll be interesting to see what they come up with.
Kittens!