The Nash trade wasn't at no expense, as the Lakers could easily be handing a top 10 pick to Philly next season.
I also don't think Kupchak expected that the Lakers would be so bad that they get two guys like Randle and Okafor/Towns. Kupchak is great, and set things up well despite the misfortune, but also got a boost of fortune. I give him credit for the position the Lakers are in, but this isn't how he drew it up.
I agree that it is probably a couple years before the Lakers are true contenders, but they'll be a playoff team in the next year or two, and could pull this off sooner. So many things are up in the air right now. The Lakers nearly swung the #7 pick in a deal for Klay Thompson last year, so there's no telling what the Lakers do this offseason with so many assets (Randle, Clarkson, #2, #27, #34). Their roster may be completely unrecognizable in a month or two.
With the cap space available, I could see the Lakers pulling Butler from the Bulls, and may be able to sweeten the deal a little with a pick. If the Lakers have Butler, Randle, and Towns at 3, 4, and 5...that would be tough for KD to turn down that opportunity. I'm just talking crazy, but plausible, scenarios right now, so I'll try not to stray too far.