Doctor Who Thread III: Reverse the Polarity of the Neutron Flow

[dps]

But because he's woven himself throughout the universe, the Doctor somehow ceasing to exist and being forgotten opens up a huge paradox that will destroy everything?

Ceasing to exist and being forgotten are not nearly the same thing. The former could cause paradoxes; the latter is just the norm for most of us, and doesn't cause any paradoxes. Put another way--almost everyone who died more than 100 years ago is forgotten, but that doesn't cause any paradoxes.