In Witch’s Familiar, we learned the Doctor can summon his regeneration energy for others. Here’s a scenario: what if Clara is injured, dying even? What does the Doctor do? Why, channel his regeneration into her. If it could work for Davros (who didn’t have any Gallifreyan Time Lord tricky DNA last time I looked) might it not work for Clara (who is, of course, Impossible)?
Could Clara regenerate? Could the next companion be Clara?