Fans have been clambering for his return ever since Coal Hill School briefly appeared again in The Day of the Doctor and became the center of the universe for ClaraWho, and to be honest it's baffling that he didn't show up. Like seriously, he was confirmed as still working there on the billboard outside the school - you'd think with the rate that Capaldick kept landing the TARDIS in the classrooms that Ian would've belted for whichever room the engine noises came from, burst in and yelled "AWH YEA! IT'S MAH NIGGA, THE DOKTAH!"
Although in all fairness this hypothetical return would literally be a copy and paste of School Reunion, and let's be honest here; School Reunion is more GOAT than (almost) anything in the Capaldi era, and would be an incredibly tough act to follow. Best not to attempt it with theMoffatwritingteam; leave it to Big Finish, after all they handled Susan's return very well.
They didn't even bring him back in Class, but that might be a good thing considering what happened to the headmaster in the second episode. BRAVO, P. NESS!
That being said, he did reunite with Eleven in the comics, where his wedding to Barbara was depicted. Sadly the closest to appearing in the revival that he's got.