Uh-oh. The next Dragonball Z anime movie has a title and a villain, and it's not good news for Goku. In order, it's Fukkatsu no F (or "F Is for Resurrection") and indeed, the first look at the movie reveals the return of Goku's most iconic foe — Frieza.
ANN got this art and official movie summary from V-Jump magazine:
An Earth where peace has arrived. However, remnants of Frieza's army Sorbet and Tagoma (from the Japanese word for 'egg') arrive on the planet. Their goal is to revive Frieza with the dragon balls. Their dastardly wish is granted, the "F" that plans its revenge against the Saiyans is revived...!
As in Battle of Gods, it appears Fukkatsu will be considered an official part of the DBZ canon. Hmm. But I assume Frieza will come back several million times stronger, seeing as Goku has gotten rather more powerful since he original battled the bad guy. Also note the return of Beerus, the unusually chill god of destruction from the last DBZ movie, on the left of the movie poster above. The movie is set for a Japanese theatrical release on April 18th, 2015.
There are no other details yet, but given how the last fight between Goku and Frieza went on the TV show, I expect the movie to be 45 hours long.