Zercia
I can't believe it is already 11th that means only one more doctor after this guy.
I'd be very surprised if that were the case.
Try this out...
SCENARIO -
You are the BBC. Doctor Who continues to be your most popular drama series.
You're up to the thirteenth Doctor and the actor who's playing him announces he's leaving.
Because some story from 1976 contradicted all previous Time Lord continuity, then fandom (a tiny fraction of the audience) all 'know' that the Doctor can only have thirteen lives.
DO YOU...
A) Cancel the series.
B) Introduce the world to the fourteenth Doctor and build some technobabble about 'a new regenerative cycle' into the plot.
It'll be 'B'. It'll always be 'B'.
What determines the lifespan and longevity of Doctor Who will always be the complex real world decisions that TV executives make based on popularity, expense, and the BBC's public service remit.
The show will stop when the BBC don't want to make it any more. It'll never, ever stop because the Doctor has 'run out of lives' according to a retcon from back in Season 14.