In all likelihood, yes, the big improvements will be with cap space in 2015, and luxury tax becoming a reality in 2016 when Ross and JV get their pay raises.
But let's also not write off the possibility that Ujiri finds a way to make a big splash this summer. If he decides DD is the piece to move, I could see it becoming a package of DD/Salmons/TH/1st rounder(s) for a superstar type player (and bad salary ballast), especially if there are some first round upsets that suggest teams need to shake things up.
Paul George and David West if Indy blows things up? James Harden if he keeps imploding for HOU? Does OKC do something rash with Durant or Westbrook or Ibaka if they lose to MEM? What happens in GS, with all the turmoil there? Are Iggy or Curry suddenly available for the right price if the new coaching staff wants to go in a different direction? What about the Clippers and the huge mess they are right now? If Sterling refuses to sell, does every player request a trade? Even if not, with Doc probably forcing his way out, new heads in the front office means question marks aplenty roster wise. Is there suddenly a market for Chris Paul or Blake Griffin?
There's a lot of opportunity to make moves this summer. Or to move up in the draft (lots of teams with reason to trade picks or with multiple picks, which usually means it's easier to part with one of them). Or to wait on the upcoming cap space. And with the team's current success, so many windows are being opened - suggesting that whatever Ujiri does, there will be options aplenty to improve the team, and he just has to pounce when the opportunity is best.