With the recent serious allegations against John Barrowman and (Especially) Noel Clarke surfacing, it looks like there's more trouble ahead for Series 13 of Doctor Who.
It's been taken for granted that the character of Jack Harkness would be turning up again for the regeneration episode. That is now almost certainly not going to happen. However, with filming on series 13 due to continue for several months it's unlikely that Jodie's final episode has been filmed yet, so there's still time for rewriting to take place.
More concerning is the fact that Barrowman was seen in Cardiff a couple of months ago, leading to speculation that he's appearing in more than one episode in the new series.
If that IS the case, and if Barrowman is 'cancelled' (As looks extremely likely), what does that mean for Series 13? Perhaps he's only filmed cameos that can be easily edited out. But if his contributions to that episode - or episodes - are greater, will the BBC opt to drop them from the series? Will they allow them to be released on the dvd's?
Season 13, an already critical year for Doctor Who, may end up comprising of only six or seven episodes.
I do not know details on such things.