[Bacl]

Regenerations are not still capped at 12, but the show-runner and producers may choose to revisit this idea at anytime, before or at or even after the 13th Doctor.

The show has long ago abandoned any sense of hard rules (or even 'soft' rules) within it's universe. Each episode is essentially independent from the last, carrying over information and history only as that one episode's individual writer wishes.

So, for example, an episode can say X is impossible. The next episode can ignore this rule as though it were never said. Two years later, however, an episode can mention the premise that X is impossible as a throw-away line or joke. Another episode may choose to act as though X has been impossible all along, despite previous episodes which were contrary to this notion. Said episode can then equally dismiss the impossibility/possibility of X at the end. All episodes that follow need not honor anything that happened in this, or other episodes.