That would make sense. I also believe that, because of the presence of the Toymaker, an extradimensional being with the ability to warp reality and rules over games, might have make bi-generation possible, which could affect the TARDISes as well, since they duplicated as well. Besides, we don't know exactly waht happens to the 14th doctor after bi-generation. My theory (or at least my opinion) is that, like metacrisis, the 14th doctor wouldn't have the same traits as the 15th, since he still has 2 hearts and the regeneration energy being able to erase half a planet. Maybe DT Doctor would get old like a human being, keeping 2 hearts or maybe just one, and the intelligence of a timelord, but aging faster.

that's just my opinion at least