This would be interesting if true. Mostly because it opens up The Commonwealth as a new fraction, not just another west cost faction transpanted into the east coast (on that note, I wonder if we'll get more of the goodguy east coast Brotherhood, or go back to asshole isolationist Brotherhood?) As others said, this has the potential to feel kinda samey to Fallout 3, so I hope they take strides to differentiate the two.
Also it means we'll be bouncing back between the coasts again. Which isn't bad, but NV left me wanting to know more about what happens with the NCR and the Legion. My ideal Fallout 4 would take place in the Four Corners region. We see what Legion society is like away from the frontlines in Arizona. The NCR moves into Utah and has to deal with the locals. We could finally explore Dog City (Denver) which was originally planned to be in Van Buren. Plus, Los Alamos and Roswell are perfect settings for Fallout shenanigans. Though I admit it would have the potential to feel too much like NV. But honestly, I'd be perfectly fine with a NV-2, even though I would understand if not everyone felt the same.