GW2 has no endgame

Aren't there raids? Kill the elder dragons and such?

No raids, and no dungeons really, more like hc scenarios, since there's no such thing as a healer or tank.

What about stuff like this guy?

I think I have enough endgame in WoW. I am thinking rather of leveling through quests and experiencing the storyline. Lord of the Rings Online was really good for that. I am thinking of trying something else. I installed Star Wars TOR which I played in the beta, but looking through some comments on their unfavorable F2P model, I am not sure I will play it.
I'll browse around to see what other MMOs look interesting besides GW2 (Secret World?). Then again, I might just check out D3 or some other "mostly single player" game. In the mean time, Hearthstone beta looks quite interesting.

This is a world boss/event, more like the ship event in Timeless Isle, not a "real raid" is needed for it.

Almost every zone have one or more events/bosses like this. Remember that your level is scaled down to the zone's level, but still you will be more powerful (by far) than a player of the appropriate level for the zone.

Well isn't there a lot of this going on or is it like "Day 2: Finished all world bosses, lawl"?

Yes, there are a lot of this going on, from level 1 up to level 80.

When you are at level 80, you can go back to other lower level zones, that you didn't level through them, to see their events and your level will be scaled down to the zone's level.

After you see all the zones and events on one character, there are not too much things left to do (unless you want to see them again with another character). The game get new events/one time special events/other things every 2 weeks.

It took me about 2 months to see all (and by all I mean absolutely all) the events/puzzles/etc on one character, and I was playing over 3 hours per day every day. For sure there is a lot of leveling content on this game.