That's not exactly an idea, that's basically what they have to do to make Fallout 3, add new places to explore. I wouldn't mind seeing the game move east though, i guess that would be towards Nevada.
But not more vaults as such, rather new and interesting ones. Quantity over quality here, that goes for more locations as well. It's not hard to make a town and stuff it with "fetch this, fetch that, kill those" quests, it takes effort to make it interesting. Towns should, with very few exceptions if any, have a purpose and be interesting to visit, not just be there so you can add 5 hours to the "gameplay time" on the back of the box.
>And what about an RV like the car but it decreases the time needed to sleep to heal your self.
First of all, the idea of an RV... No.
Second, it'd render the trait Fast Metabolism useless, along with one of Endurance's pros. And that stat has few enough pros as it is.
Consider how the car's trunk in FO2 made carry weight utterly useless including the
two perks associated with this stat. What's next, Ring of Strength +1, or Gauntlets of Agility