I imagine that login retrictions will be fixed by next week. A few things will happen.
They will block character creation on existing full worlds. So you will have friends who are not connected and want to play with each other. They then will open new worlds, so those people who are locked out, and thier friends in the congested worlds will likely bolt to the new server. This is more true for the FC and people who didn't have EA. Though we couldn't play, at least you could create your character.
Even if this helps another 30-40% of people to login to their respective servers, it will diminish the need for AFKers to stay logged in which will also help with congestion.
I'm afraid they will add too many worlds, and when the initial hype (the first month) is over, their won't be enough population. A problem to be solved later I suppose.