You guys are being way too optimistic. This is SE we're talking about.

Open Beta STARTING in January. NOT December.

Ending????? Who knows.

2.0 Launch? Probably late February. Early March.

Q: When will Final Fantasy XIV 2.0 launch?
A: I expect the first Closed Beta for the Japan and International servers to be held end September or early October, entering Closed Beta 2 this winter and Open Beta in January next year
ALSO:

Yoshida previously said during the server consolidation that the current servers would also be used for 2.0. Because of that, 1.0 will end when 2.0 goes into beta. Since open beta doesn't even start until January, you're looking at some extensive downtime until actual launch.

GE: Speaking of Beta, will there be downtime between current game and 2.0?

Yoshida: What’s going to happen is that after the current version is finished and storyline over, the servers will go down and the 2.0 beta will start up.