September 2011 is the near future to you? Because that's when RAGE is coming out. Hunted and Brink are scheduled to be released in 2011 too. Unless you think Bethesda is going to wait aaaaaalll the way until after September 2011 to announce it, assuming they don't announce even more new published games that would come out afterward, Bethesda isn't worried about ruining the hype. Even if they are, then they're screwed because there is no date during which they wont be publishing a game until after September 2011.
Todd said that it will have a shorter release window that any previous Bethesda game. I think an announcement sometime after FONV is likely, especially if they're alternating franchises. Once FONV is released, that'll free up some marketing so they can focus on Brink, and start trickling out information on ESV. I'd say September 2011 or sooner would make sense, since the way Todd was talking, it's fairly far along in development; or at least to a point where the project is starting to come together as a whole.
I don't think it's a matter of hype, I think it's more a matter of marketing resources. Bethesda isn't EA. They may have money, but I think they'll need the money from another Fallout game to fund their upcoming projects.
**EDIT**
Near future in terms of an announcement for me is sometime before holiday 2010. My personal belief is fall 2011 for the release date.