Doc Brown appears to be alive again, in the Old West, in the new Seth MacFarlane movie "A Million Ways to Die in the Old West".
http://www.imdb.com/title/tt2557490/...f_=tt_ov_st_sm (Note: Christopher Lloyd as Dr. Emmett Brown)
A friend of mine just saw the movie trailer (at Spiderman 2) and Doc Brown was at the end of the trailer, covering up the Time Machine
and explaining that it was just a "weather experiment". Two different BTTF references together, but it appeared to be well executed.
I checked the online trailers, both the regular teasers and the age restricted teasers, but no signs of Doc Brown in either one, yet.
http://www.amillionways.com/