Blizzard already has the tech to easily create one or more servers and limit realm transfers if/as needed and limit auction house integration... Likely some folk that don't really multibox but don't care much about it would also create characters there (for example, just in my case, my brother and at least 3 friends also would create characters there). It would be easy to do and likely a single server for that would have more active population than some of the other servers...
There are lots of dead servers currently and really they should look at merging servers after the TBC Hype dies off and the active server populations go back to a relatively steady state. My understanding is that their servers are VMs with underlying hardware hosts so they should already even have the hardware capacity via flexible ways of growing/shrinking VMs (including shards/etc).
I don't think Blizzard would do it but it isn't difficult nor beyond current capabilities (nothing really new would be needed).
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