This is to be a stress test and I doubt that everyone will be able to get on for a few of reasons.
Firstly, I expect it will only run for a while so that the concentration of people is increased.
There will be a huge lot of people trying to give it a go, all at the same time.

The reason for this test is not a 'beta' as some have said. It is to put stress the ability of the Core3 server to handle a large number of connected clients. If they find that the server can only handle 80 people before lag or frame rate issues they might have to change stuff. If it easily handles 600 then I'm guessing they'd be happy. But please don't think they're doing this as a teaser, it's a sensible developer decision made for development reasons.

I'll try to get on it (as will most of us) but only to add my weight to the throng of others. If I can't get in - no big deal for me. I really hope it works well for the Dev Team and they get what they want out of it - I'm looking forward to the finished product.