Fallout 4

http://en.wikipedia.org/wiki/Fallout_series#Fallout_4

Nothing on a release date, but still.

I wonder if it's possible for them to do something like what Mass Effect did with transferring data files.

It's possible, I suppose, but I don't think so. Levelling up in Fallout is way more important than in Mass Effect, while choices in Mass Effect were way more important.

To be honest I'd much rather have TES5 than any number of new Fallout games (until 4).

I wouldn't expect to hear anything about this until Elder Scrolls V