In an interview with RadioTimes.com, Capaldi announced:
“I’ve been asked to stay on, but it’s such a long time before I have to make that decision. Steven’s been absolutely wonderful, so I love working with him.Although this does not really give us a clear answer, it shows that Capaldi is also thinking about the decision. For now we still have Capaldi's Doctor in Series 10 to look forward to, but we will keep you updated with any further news about Capaldi's decision.
Chris is fantastic, and I think he’s a hugely talented guy. I don’t know where the show’s gonna go then. I don’t know. I have to make up my mind, and I haven’t yet.
As Steven will tell you, it’s very difficult to say goodbye.