I hope not, and I think not. Yes, being the only actual game out for the 360 for months was a contributing factor, but now, like i said, they're big. They don't need to resort to cheap tricks like that to sell, now it's like mario or Legend of Zelda, their reputation alone will sell games.
You are correct about Bethesda being big, but why go into battle with a big army when you could go into battle with an even bigger one?
The main reason why I think they are waiting for the next generation of consoles is because if they weren't they'd have probably anounced TES V by now. Another thing is that the current generation of consoles is nearing it's end. There are speculations about a new generation coming out in 2011 or 2012. While they might not need TES V to be the first game available for the new xbox, they probably won't want to be one of the last for the xbox 360.
And they'll want TES V to have better graphics than Oblivion.
I think one TES game per generation is actually a pretty good idea. It gives each TES game enough time to run it's course, they have plenty of time to gather player feedback and see which mods are the most popular, and last but not least it gives them the opportunity to really polish up the game.
That and it gives me enough time to save money for a new computer.
Lately, more and more I've been dreading the prospect of ES:V being an MMO.
Don't worry, from what I've read in interviews with Bethesda TES V isn't going to be an MMO. We might get a TES MMO in addition to TES V, but TES V is going to be a singleplayer game again.