I feel like Hanselman is one of the few old generation Microsoft people. When he leaves it’ll be young people who don’t know Microsoft and have no understanding of or connection with Microsoft products.
I don't know about his career in general, but Hanselman once spoke at a conference I was helping organize here in Thessaloniki, and he was great. Really knowledgeable and very down to earth.
Dave Cutler and Raymond Chen might like a word.