It’s basic SF aimed at kids.
It’s basic SF aimed at families (these days, anyway).
can the next Dr Who be female, or gay, or ethnic, in a wheelchair, just anything not an able-bodied middle aged heterosexual white dude.
The introduction of Missy is a double-edged sword here. On the one hand, it’s set precedence that a Time Lord’s gender can change; on the other, the fact that they’ve just done it probably means that they’re unlikely to do it again for a while. I can’t envisage them making both the Doctor and the Master female at the same time, and Michelle Gomez is so deliciously batshit that I can’t see her going anywhere any time soon either.
Ten was a bit orientation-fluid under RTD, remember the whole thing with Jack Harkness? And Idris Elba was in the running for The Doctor at one point (I’ve half a memory that he was actually offered it and turned it down).
TBH, I think the next Doctor should be whoever’s right for the role, regardless of gender / skin colour / etc; picking someone because they tick a demographic would be a mistake.
Though, given that the last two regenerations expressed surprise at having teeth and legs, a female regeneration has the potential to be hilarious. (-: