[kevkrom]

Well, there should be a portrait of Snape in the headmaster’s office.

One could make the argument that Snape was no longer Headmaster st the time of his death.

[Politicalmom]

I just read an interview with Rowling a couple days ago.

She said he effectively abandoned his position, which is why it wasn’t there, but that she thought Harry would have seen that one was installed at a later date.