This is my idea of how it should work:
1- Every race should “return” to their capital city in which you will have all the commodities you need to live in (AH, flying, etc).
2 - You won’t have access to a city you are not from.
3 - Cut the org/SW main city crap + faction nonsense.
4 - There will be a main city (like Dalaran) in every xpan that every race will have access to.
5 - let every INDIVIDUAL do whatever (s)he wants… if a Belf wanna hang out with a Velf and kill Gnomies in the OW… there you go!, if an Orc wanna kill another Orc because, reasons, there you go!..