I was just thinking about this too. I was playing GW2 for a few hours earlier and it seemed deserted. I remember seeing people in Lion's Arch, the main hub city, but I don't remember seeing anyone out in the open world. It seems most of the players on that now are in dungeons leaving most of the world empty.

I hope ARR does something to address issues like these because it was seen in the original FFXIV too. As most people get into the higher levels there is little reason for them to go back to the lower level areas. This leaves you with most of the world being empty and can be discouraging for new players or those coming back after some time away and can leave high level areas, if not instanced, over crowded with most of the population fighting over limited resources.

I think one way ARR could handle this, as well as using low level areas for through trafic to higher level zones, would be to introduce higher level leves to all camps, not only new ones. This depends a lot on how the balance of activities is in the upper levels of ARR.