I am not so sure that is a separation though. Dungeons do exist as a game mode in GW2, but don't really have the same purpose behind them. Whereas say the leveling game 1-84 is a totally different experience and goals then 85+ in Warcraft. There is essentially two distinct games; pre & post 85.
Obvs, a bit of marketing by Anet. They might be full of it come release. On the surface, there really doesn't to be anything that shifts in focus at L80.