This is impossible. Some players have saves on multiple servers, if two servers merged then these players would have to start again from scratch; and I don't see that going down well. Combining severs wont really solve anything as next year, during Summer when everyone is free again, there will be another massive influx of players. At that point there will be huge queue and everyone will complain and ask for a new server. Then after a few months the player count will die down again and there will be posts like these popping up on the forums every now and then. I feel that this cycle will continue for as long as PRO exists.
Also, don't worry about this. Staff are bringing in plenty of new apprentices who will be able to help moderate the game :)
If still like now , i think PRO can't wait next summer.