THis is exactly what happened on AION, Lumiel, which then became Israphel, was the strongest ad most active server, and a big part of that was the active pvp-RP guilds.
I also strongly believe that we have an advantage in the long haul. Many of the other average servers will see their populations decline as people jump ship to bigger servers, however because we are the only RP server our population should always be steady. As the times goes on and many of our roleplayers and explorers start to enjoy more time in WvW I expect us to do increasingly better. In many games the RP servers are actually the highest populated servers or near the top.