From what I could tell, it was just speculation. They went off the Core A and Core B thing which has been more or less confirmed in that Oha Suta interview.
Does anybody know what happened to Chespin in the Mega-Evolution Special 4 after it came into contact with Zygarde Core? I wonder if it absorbed too much energy from Core, and if it's the same life energy that Megas, Primals, and Infinity Energy comes from?
Also, this:
https://mobile.twitter.com/Pokemon/status/660186329108451328
^That is most likely referring to "one more day till Halloween" because of the creepy Espurr pic, but I'm loving how people are freaking out that it will be a game announcement.