KC isn't pursuing anything now, but the arena being built was originally an attempt at getting basketball, hockey, or both.
I don't see the good of building an arena short of a guarantee from a league that can be codified in a contract. Otherwise, you well may just waste money on an arena or stadium for no reason, and honestly, there are more important things to spend stadium money on even when you DO have a team for some especially broke areas.
To tie this to Seattle though it's off-topic, it would make a bit more sense to build the SoDo arena because the NHL clearly wants to stick a team here, and it would be a good way to get an arena built now and have it for later if you hope to entice the NBA back here. However, I would still want the builders to get a promise of a team from the NHL first (and this is all moot because Hansen isn't going to build for NHL first - precisely for the reason that there is no promise that even if he does build, the NBA will be back).
In terms of L.A., I don't see why you would build a stadium in City of Industry or wherever unless you knew for sure that you had a team coming.