so this just happened. not sure if intentional or coincidence
WHEN IT IS TIME FOR THE DOCTOR 100th ANNIVERSARY SPECIAL:
Matt Smith will be 81.
David Tennant will be 92.
Christopher Eccleston, if he is still alive, will be 99.
And Paul McGann will be 104 and not have aged a day.
So that means we already know what 3 of the four will look like, then.