Blizzard are one of the only developers left that are PC-only, but it looks like this could change. The developer are testing Diablo III out on consoles, and have said that it could eventually turn into an "official project", which would see a departure from their PC-only stance.
We heard rumblings of a console release earlier this year, but haven't heard anything else until today. We might eventually see Diablo III, and previous as well as future Blizzard titles reach current- and next-gen consoles. Rob Pardo, Chief Creative Officer at Blizzard has told Polygon:
We're still kind of exploring it. We've got builds up and running on it. We're hoping to get it far enough along where we can make it an official project, but we're not quite ready to release stuff about it, but it's looking pretty cool.