Reboots can descend into tick-boxes of origin stories, but when time travel is inherent in your premise, you can afford to have some latitude. Whereas J.J. Abrams had to have his Spock explicitly state the timelines are being altered to avoid a few death threats from Trekkies, Doctor Who can and should be a bit more playful with the tedious notion of the canon. This hypothetical US Who already has a more mysterious Doctorit could go further. Even more than BBC Wales, the mythology is up for grabs. Dont like the Master? By all means invent your own enemyWill Arnetts another Who fan! Would you rather the Doctor is a human with regeneration a time-travel-related super-power? The Daleks say as much in The Evil of the Daleks! The series changed its own premises so wantonly, you may be hard-pressed to out-contradict them.