Hm, a nanite/liqui-metal combination forming itself into a coral like network to form the basis of the entire structure would still fit. I just thought it was interesting that the Radio Times teased the baby Tardis sapling taken from the first one. As really, although it's a baby now, when it achieves adulthood it could travel back, they could have had a Jack from the future turning up with the offspring Tardis. They still might lol.
Something as large and complex (and old) as the Tardis with advanced enough AI could achieve some form of sentience either way.
It's the "permanently dying" star that annoys me, as if it's on the verge of becoming a singularity, the amount of power needed to hold a star about to supernova is probably more than the thing is giving out, and gravitationally very hard to compensate for when inside an already carefully crafted spacetime pocket.