SilverStar17
Super Freak
I'll have to watch TFA again, but if he left his helmet on the catwalk, and didn't wear the long robes when squaring off against Rey and Finn, I'd agree that there is quite a bit of room for change in the look of the character. I'd actually prefer no helmet in VIII, or at least not until the end of the Snoke/Ben training montage or end of the movie. If it follows ESB cliffhanger-style, I could see the final shots showing Kylo putting the new helmet on...in preparation for Episode IX.
Being that he'll likely have a scar on his face, I can see him still wearing a helmet/mask in Episode VIII. The scar at least gives him reason to wear one now other than merely attempting to imitate Vader.