So after Kalin event, it's back to Gx for Yubel, after that, i believe it's to DM for a Weevil Event for a few new Inzektor cards then what? Maybe after these events or by begining to Mid November, Sera may be coming. Just a guess.
It could be December. But i think november because after Unknown duelist showed up in DSOD, we're going backwards. After sera avatar form, we went to 5ds for Kalin, then going back to GX world for Yubel, then back to DM world for Weevil. See the pattern? Possibly, we're headed back to DSOD