as long as we're overgeneralizing, "serious" HTPC users will always have a TV tuner hooked up. It'd be silly to buy an HTPC to do something that a $50 wifi BR/DVD player can do.
Lots of people do things on their HTPC besides watch movies and TV. I have a home built HTPC in the living room and have no interest in hooking up a TV Tuner. I consider myself "serious."