http://elderscrollsonline.com/en/news/post/2014/03/14/eso-road-ahead
Not much in there, but tqwo main points:
1. Craglorn, the Adventure Zone of legend, will now be in the first post-launch update.
2. They have bought and installed an overflow server, just in case too many people swarm the main one at launch.
Pretty safe to say, based on the latter, that they're not going to have half the problems with overcrowding that many other launches had *cough*FF14*cough*