I’m 827% positive that the reason Anderson doesn’t think Sherlock is dead is because Sherlock purposefully let Anderson see tiny glimpses of him the past several years, just to screw with his head. Appearing through Anderson’s window in the woods, standing across the street of his favorite coffee shop, leaving small traces of his presence in his office.
Because Sherlock’s a little shit like that.
so there’s that scene where clara goes ‘someday, you could just walk past a fez,’ and eleven responds with ‘never gonna happen’
and i bet that someday there’ll be a scene where twelve walks right past a fez and clara watches him and she looks so sad for a moment because it really hits home how much she misses him