Well, a few things:
1) That site isn't official, and a lot of their information seems slightly off (they somehow ignore level scaling in PvP in their first point).
2) I don't see anything in there saying that you will only have 6 dungeons. In fact, it specifically says that you will have the chance to revisit every old dungeon, but updated with higher-level content.
3) Adventure zones.
4) You will have access to other alliances' territory.
5) Etc., etc.
Long story short: there's going to be plenty of PvE content.
Edited for above: As mentioned in at least one preview, beta content was abridged and level-capped. No one has seen endgame content, period.