Skyrim Mobile is the proof.
Oblivion mobile isn't a Travels game. At least it wasn't considered part of the Travel series.
Consider they have been working on a game for Two years, around the time of the Skyrim Mobile popped up. Coincidence? Obviously the next game will have a Mobile counter part, called Skyrim mobile.
They didn't know if Fallout 3 would be successful and therefore it was to risky to have a Mobile game made as well. BGS studios doesn't actually make the Mobile games they get some other guys(TKO Software and Vir2L Studios) to do it. And these guys may not have wanted to make a Fallout mobile.
I would just like to chime in and mention that while you may feel very sure of something, nothing is certain. Everything we say in here is purely speculation. In your recent posts you seem to be taking this website and using it to say that not only are they making TES V, but they are making a mobile version as well. But the thing is, none of that is any more than speculation. I'm just saying, this website isn't "proof" of anything, so you shouldn't act like it is.
That said, I wouldn't be surprised if this .mobi site is a relic from back before they essentially scrapped the mobile game Todd was talking about. It could be that the mobile game was indeed a mobile version of TES V, and they bought the .mobi site for it, but they then decided to cancel it and decided to just let the domain expire on it's own.