Well, for example, there is a lot of raiding to be done. At the moment we have at level 80 3 Extreme Trials, 4 Raids (Normal and Savage (Hard) Mode), 1 Alliance Raid (24 People) and 1 Ultimate. Those numbers will propably swell up until the next expension to 7 Ex-Trials, 12 Raids, 3 Alliance Raids and 2 Ultimates. Ultimate is the hardest content there is, content which may keep you busy for months until you get the clear. Progressing in Savage-Raiding will also take you a while.

And then again, the leveling won't stop just because you hit level 80 with one job as you can level all the jobs, crafters and gatherers up to level 80. And if you are new there is also a lot of old content to catch up with mounts, glamour and other stuff to collect. This game will keep you busy for a while for sure.