The "Seattle is getting the Kings, Sacramento will get an expansion team" line of logic has never made any sense to me.
First off, (and I feel I've said this countless times now) WHY would the NBA uproot a franchise, erase its history by changing it from the Royals/Kings to the Supersonics and THEN turn around and give that city an expansion franchise in a few years that would go back to being the Kings? Why?
The Seattle group could make their plan work with the promise of an expansion team. I would think that would fufill the terms of their agreement to move forward on a new arena and the reborn Sonics would start play in a couple seasons either in Key Arena for a year or in the new SODO arena. But I can't see things working out that way in Sacramento. If the NBA leaves, I'm pretty sure it leaves. The new arena, the downtown development, the ownership group, the parking revenue are all contingent on Sacramento having a team, not the promise of one.
Because it makes no logical sense I can only attribute this line of thought to Seattle fans who understandably want their team back but also want some way that Sacramento and it's fans are decimated in the process. Sorry to say, but it isn't going to happen. If the committee recommends relocation and the BOG approves it I'd be surprised if the NBA ever returns.