I've also been on the "February cover" boat for some time now, but remember the DA2 cover? We were all dead sure it was TESV based on the fact that fantasy fans would love it (and I did). Remember to beware opinion myopia. Half-Life 3/2 episode 3 and TESV are both high up there for people, but there is certainly more. I'm not saying it's impossible, in fact based on the February idea it seems fairly likely, but still. Beware the overanaylsis of Tweets, as Antibody says.
February seems very likely. I'd say that it could be announced at the VGA's, maybe Beth will release a few screens, or something of the sort. We crap in our pants for a month while the game is hyped out of control, and then they drop a Game Informer with some juicy info.
I can only hope.
I would bet that Half Life 3 is getting an announcement soon as well, but my guess would probably be later than February.
Although the tweet does say, "you've been waiting for this one forever". That could be anything. Heck, I guess I actually wouldn't be that surprised.
But nevertheless, even if February isn't TESV, then I bet we would still get a cover within a couple of months.