Most likely not. The episode sets up that only Greninja can see the vines, and thus he must stay in Kalos to protect the world and Kalos, should the weapon used to create them, rise again. After all in the legends Ash Greninja was the hero of the ninja village, now it's the hero of all of Kalos.
So it coming back seems unlikely, but you never know. Maybe Zygarde gets to Alola somehow and hides out there. I doubt that though, but you never know.
It's sad to see him go, but it's a nice story, even if I'm slightly disappointed by results. It still makes sense. On the plus side, Goodra is still available to be called on. It be cool to see it come back sometime in Sun and Moon.