They need to merge Data Centers for PvP, keeping them separated is only shrinking the already small population that is interested in doing some PVP.

Also introducing a system that will let you join a game regardless of your GC (like in the game Rift for istance), playing as a "guest" in one of the opposite factions, could be a great way to alleviate this problem. I know this solution is not lore friendly of course, but when the alternative is to wait 40+ min for a match, then the lore can take the backseat for once in my opinion.