What they need is a mechanic that automatically merge a server as it ages. So they can keep opening new servers to give new player opportunity while at the same time does not increase the actual number of server remaining.

That said, if it is to be automatic, the mechanic and merger needs to be scheduled BEFORE the server is opened and published. Ideally, each 2 month or so worth of server of each region would get merged into one over the course of roughly a year by performing multiple intermediate mergers: you start w/ say 16 (2 per week per region), and turn that into 8 say 4 month in or so, then 4 at about 6 month in, then 2 at say 10 month and finally 1 at end of year.

Once the system gets going, the total number of server won't increase much, yet at the same time people can play in a new server just about anytime and won't be beat down by older player until they had quite a while to prepare.