This would be a cool feature to add to eq2 to help with the ever so frustrating low server population issues. https://www.guildwars2.com/en/news/guesting-is-coming/
A cool feature, yes. Will it work? Probably not. Dungeon Finder isn't even cross server, and we've had it a while.
No they won't do this cause then they will have to get rid of the transfer tokens and no longer make money from them. Guesting will be like a free server transfer. SOE is all about money.