If it happens, I dearly hope that it's made in the UK. IMO, Americans just can't do British TV and films (q.v., Miracle Day).

It would be great to have it be canonical, as part of or an adjunct to the series. It wouldn't be much longer than a two-part episode.

As an alternative, maybe Paul McGann can be recruited to flesh out his regeneration a bit. We only have the TV movie hors d'oeuvre. An entrée (or a main course) would be tasty.