I don't know is this is the official site for stuff like this, but:
I definetly think it's true because of this:
http://generatorrexpedia.wikia.com/wiki/Ben_10/Generator_Rex:_Heroes_United#Trivia
It says:
- A sequel has been hinted:
- Six voiced that it was possible for Rex and Ben to meet again some day claiming that fate works in mysterious ways.
- At the end of the episode it showed Alpha breaking free of the containment ball in the Null Void.
- A sequel has been confirmed in an interview with Man of Action as they say it is a 2-part special.
Logo or Promo?
Comments?