As I mentioned recently, I already know what I want for a Live Expansion... I want Sylvania and Drakenhof Castle.
Sylvania is the home of the Vampire Counts, specifically the Von Carsteins, warhammer's classic Dracula style vampires. Being Warhammer they are a bit more aggresive than Bram Stoker's vampire, with world domination and an eternity of night well and truely on the agenda. The land they call home is the classic European vampire setting, dark, decaying, gothic and oh so very atmospheric.
I would want 3 zones. The main countryside outdoors, the crypts and dungeons as a huge underground zone and then Drakenhof Castle itself as the third area. All of which would be fully RvR enabled and NOT instanced. There would be boss PQs like the Colossus requiring players to work together to activate them, also lairs and other epic feeling events, but all of which would have the risk of enemy players attacking. There would also be lots of RvR themed PQs that would affect movement within the zone itself and add a further tactical element. Bridges to destroy, caves to collapse, that sort of thing.
I would suggest lots of things that could be done communally, not just with 1 group. Perhaps to activate major boss events and special RvR activities. Then the big crunch would be in Drakenhof itself, some kind of hard to reach and hard to win event that would have a positive impact on the faction that manages it. Something that would be worth the effort, but at the same time is not over powered.
The basic concept is full RvR, non-instanced zones that don't lock, are not gated and have loads of fun things to do. A place where all PvE has a risk of PvP attacks, but has rewards that merit the risk for all involved, both those trying the PvE and those attacking them. Everything organised and spread out in such a way that it promotes small group play and limits the effect of zergs.
Not exactly a new concept, but one that will do me I reckon :)
Update: I forgot to pimp Oneshard's WAR video. It does a good job of showing how much better the game runs now and if you've not played WAR before, it certainly gives you an idea of how you can PvP all the way to 40 :)