One of the main problems given by Blizzard on this is character names, tech is something that can be developed, but forcing players to change their long term and much loved character names would indeed cause uproar among the masses.
How would you merge servers and combat name changing issues?
One thought I had would be with merging 2-3 servers at a time giving priority on names to characters with most /played time so placeholder names and seldom played alts would not poach names of players actually adding to communities. Also ex-players that have highest /played on a name would get 30 day notice to claim that name before they lose it to the next highest played character, and so on and so forth.
Then on the other hand is what is probably being developed by Blizzard, and that is the battletag system being used in D3 currently, which is more than likely being developed for use within WoW, making all characters play under your battletag name and can take whatever character name they so choose. Along with this, they may implement a name to be unique to faction and class, so you don't have 50 paladins on one faction called bubbles, but you may encounter a paladin and a priest with the same name on a single server.
GC has stated in the past that heirlooms want a new system that doesn't require mailing and can be account bound not server bound, and also that gold may become server/account wide at some point which also points to a similar system.
Any other ideas? Would you be happy to lose your characters name to a player that used that name more often?