KC built the arena to get a hockey team, that's why the Penguins were threatening to move when trying to get a new arena, because KC had one. AEG owns Sprint Center, as well as the Kings, which is why there is none in KC.
Seattle and Quebec don't have readily available arenas. They would be playing in old arenas while they wait instead of a state of the art one.
Yeah, Sprint Center does great with all the concerts they are getting, but I would love more live sports here. OKC getting the thunder was such a joke, but that's a completely different topic.