Peter Capaldi cannot be regenerating during 2017 season
By: +David Herron; Date: April 12, 2017
The 2017 season official trailer ends with Regeneration Energy clearly emanating from Capaldi's hands as he appears to be struggling. Did that mean Capaldi's Doctor will regenerate during the season, and someone else is playing The Doctor for the Christmas special? Today, Cultbox is reporting that Capaldi is filming Christmas Special scenes this summer. Therefore, he is The Doctor for that episode, and presumably his Regeneration is at the end of the Special.
Series 10 Trailer #2 - Doctor Who