While it's certainly no lock that he's ready to return from his injury, former NXT Champion Sami Zayn is currently advertised on WWE.com for all of NXT's UK Tour dates in December. This includes NXT TakeOver: London.
Zayn has been out of action since May with an injured shoulder, last competing against Kevin Owens at NXT TakeOver: Unstoppable. Zayn sustained the injury earlier that month during his entrance on Raw, where he took on John Cena for the U.S. Title.