Ok so its clear Blizzard want to make an E sport out of WoW, but what about taking it outside the arena? Wouldn't a Warsong ladder system be great? A system like arena but applied in the WSG setting, you create a team, a roster of perhaps 10-15 people, and have the option to pick a team line-up for certain games, you queue and face other teams, be it horde or alliance from other servers to face off in competitive 1on1 WSG! - I can tell you I'd love to compete in a laddersystem and be able to have rated opposition to play against, it'd be one of the few instanced-bg events/laddersystems I could really see myself getting into, people love playing team play in WSG games particularly if they're in one with people they know, in some situations you may end up being 2-0 down and then you pull it back 3-2, those are the moments that really are fun in the game imo and will always be, the idea of being able to improvise in the event of changing circumstances would be really cool and add lastability and different outcomes to the game, you'd be allowed more leeway even in a highly competitive game vs another good team, in the sense that it would be out of 3 caps, rather than one arena game, you have a 'best out of 3' approach, rather than arena, were one lagspike or bad move can cost the game.
Picturing WSG displayed on 70" Plasmas or massive projectors to an audience showing competative teams facing off vs one another would be an equally as competative and much more entertaining thing to make an E Sport out of than arena if you ask me
I don't know why blizzard didn't implement a system like this long before arena came, but it would certainly have potential to be one of the funnest rated/ladder-style systems currently in WoW if you ask me, I really hope blizz will consider something like this in the future, it would certainly give BG's a new lease of life.
Don't get me wrong, you could also rotate it between other BG's like EoTS and AB, but I think WSG would be the sweetspot in terms of competitiveness and interest.