Will Zygarde finally get a closure in Ultra Sun and Ultra Moon?

Sina and Dexio say its unusual that Zygarde is in Alola, that it might mean something and that we may find the answer but we never did

Then there's the resolution cave in the post game which is a replica of Terminus Cave where Zygarde was in Kalos. Also in that cave we find Guzzlord which is very similar to Zygarde in many ways

The official promo art for new games has these green-yellow beams of light surrounding Necrozma-Solgaleo/Lunala which looks very much like the moment when Zygarde is transforming into perfect Zygarde as seen on the screenshot in the middle. Coincidence or its a sign of Zygarde?