Yeah, I don't see the signing of Holiday as being the result of a choice. I think their hope is to keep everyone. They hope White signs an extension, he might, maybe more likely than not, he tests free agency, but then they can pay more than anyone to sign him as a FA. No choices are off the table at this point.
I think that in almost any scenario, one of Brown, Holiday, or White is going to have to be traded at some point. But that point isn't now. For now, they keep all three. Signing Holiday wasn't making a choice, it was kicking the choice "can" down the road. They can keep everyone for next season, save some money next season, and still have all options open for beyond next season.
It might be Brown that they trade, if it comes to it, and White stays on a big contract. Maybe they trade White this off season (if he doesn't extend), I hope not, but they will get a lot more for White than they would for Holiday. Or maybe they sign White to a big contract and trade Holiday. All options are still available. Or maybe with the cap going up and who knows what else, they are able to keep all 3 beyond next season.