What proof do we have that Todd Howard and Bethesda don't want the next TES game to be an Action/Adventure game (ala Zelda or Fable, but open-world)?

There are only so many RPG mechanics you can streamline, until your game ends up being closer to Zelda/Fable than Morrowind/Dragon Age 1.

No proof at this moment, but its not likely that they'd do that.

why would they do that when the style they do now is loved... it'd be foolish to change something so amazing. elder scrolls format: stay or ill give up on humanity

Its more about the direction the series is heading.

5 years from now we have to ask ourselves if we expect Bethesda to continue making RPG titles when they're clearly a rare commodity even in present time. It will only be more apparent 5 years from now.
Since Bethesda is following suit of the rest of the mainstream gaming development companies, I think it is sensible and logical to expect them to follow the continuing trend.

There are only so many RPG mechanics you can streamline, 'til your game ends up being closer to Zelda/Fable than Morrowind/Dragon Age 1.

Bethesda hasn't announced any upcoming games so we don't have proof of anything concerning their future plans.

Demanding proof in a situation like this is at best unnecessarily confrontational, and it feels like trolling. If you wish to discuss potential future titles please use http://www.gamesas.com/index.php?/topic/1242906-official-beyond-skyrim-tes-vi-3/ and be a bit more civil about it.