On working with Tennant during The Day of the Doctor, Smith said:
“It was a real historic moment for me. I always look at David and go, ‘Oh my god. It’s Doctor Who! David is a great guy and a good friend. It was so fun. Doctors in the same room is just magic, isn’t it!”
“I’ll happily come back for another anniversary!”We're a way away from the 60th anniversary, if there is indeed a multi-Doctor special that year - but with the 10th anniversary of revival Doctor Who in 2015, could Smith's return alongside be earlier than the far-off date of 2023?
[Source: Doctor Who TV]