Harden and the Thunder are fighting what all teams who have more than a couple of max contracts are seeing. It's why players like Manu and Jackson are in for significantly smaller contracts. It's why the Spurs need to trade some of their assets (Bonner, Jackson, Neal) for DRAFT Picks to replenish the system with younger, cheaper players. I'd try to keep Curry and Powell with their much more cap friendly contracts. See below for how it affects teams.
"Under the last CBA and the first year of this one, a team that goes over the salary cap is taxed dollar-for-dollar for the overage. The new system, starting in 2013-14, will enforce penalties of between $1.50 and $4 for every dollar over the cap. Eventually, teams that have gone into luxury territory the previous three seasons will face something called a repeater tax and owe even more. Don't ask; it's gruesome."