So there are lots of rumours on twitter and elsewhere that Tennant has been invited to star in the 60th anniversary - but not necessarily as The Tenth Doctor. Or even the next regular incarnation - talk is of a “special doctor”, like a limited appearance. Other high-profile actors said to be in the mix too. Huge pinches of salt required.
More speculation
https://twitter.com/i/web/status/1484662734113456130
I can see him being in an anniversary special, but I don't see him actually doing what the Curator suggested last time he showed up, namely being a Doctor wearing a previous Doctor's face.
Imagine him coming back as the 14th doctor?