I say this because I don't think Zenimax will want to promote two action-RPG games at the same time. Seems to me I wouldn't expect TESV info before New Vegas is out the door, or at least given a firm date and some broader marketing push.
Maybe E3 will have "Hey, New Vegas is dropping in early August, buy it!" and QuakeCon will roll out TESV info.
Random thoughts.
The April issue of "PC Gamer" magazine has an article about NV, claiming it will come out in Fall. (It's set three years after Fallout 3 by the way.)