Whenever people talk about the limit to the number of generations I wonder how much attention they've paid to the canon over the years.
Think about the Master. He actually used up all his regenerations once and was granted another cycle by the high council. So was the limit of 13 a limit imposed by the high council? If so then the limit would presumably disappeared along with the high council.
Also SJA is considered part of the canon in which the Doctor says he can regenerate 507 times. Is he lying?
Then there's the fact that River used her regenerations to save the Doctor when his regenerative ability was suspended. Does that mean that the Doctor now has River's remaining ten incarnations? If he does is that 10 added to the 13, the 507 or the 11 he's already had.
I don't think the writers will have a problem in finding a reason to give the doctor more generations.