Some interesting points of view here. I haven't been following the show nearly long enough to have any input but I do agree with some of the stuff said about the writing.
Well couldn't a "cycle" just refer to one body's "life"? I'm not all up on my Doctor lingo, but that's a pretty obvious interpretation to me.
But he says regeneration cycle; Cycle meaning multiple events and Regeneration being the event.
Please don't think I'm seriously worried about this, but I must point out that is not the only way to define the word "cycle."
For instance, the dictionary on my laptop has a whole list of definitions, and the first two lines are:
-A series of events that are regularly repeated in the same order
-The period of time taken to complete a single sequence of such events
So a regeneration cycle could refer to a series of regenerations, but it could also refer to the span of one regeneration. Ya dig?
Like snowdog said, it doesn't really matter because they will always find a way around the "rules" to keep The Doctor around, I'm just saying it's jumping to conclusions to assume that he definitely has 12 more.
Okay I actually left a sentence out when I wrote this, let's edit:
The origins of the term "regeneration cycle" in Doctor Who come from the 20th Anniversary episode The Five Doctors, where the High Council of the Time Lords offer the Master, who was presently out of regenerations and could only live by stealing bodies, a new regeneration cycle. It's the old series term for the full life of a Time Lord, all 13 lives. Given that Moffat directly referenced the episode in question in the Time of the Doctor-when the Doctor mentions taking the seal of the High Council from the Master-it's a safe bet that he's suggesting the definition to be another 13 Doctors, not that they'll have to answer this question in a couple years down the line.
As the series has defined it previously-and as the hardcore fanboys will most definitely argue for it-regeneration cycle means 13 more Doctors. Capaldi plus 12 more, barring any incidents that are like how 10 saving his life with regeneration energy became a regeneration after the fact.