I like Jeff Green - I think he'd be great on the Rockets - but he's the most expendable member of the core of that team. I don't think they have the money to keep all of them together - especially if the new CBA turns the cap into a hard cap. The Thunder have Durant, Westbrook, Green, Harden and Ibaka coming up for renewal pretty soon and unless Ibaka, Harden and Green take below market deals at least one of them has to go.
Jeff Green is a Soft player. He doesn't rebound well and lacks post moves. He's like an poor mans LaMarcus Aldridge.
It's hard to say that all of those players will receive Max deals or near Max deals. Kevin Durant you obviously max out with the quickness and Westbrook is heading towards that direction. IMO, Green, Harden and Ibaka still has to prove their worth and Presti has 2-3 years to evaluate what they bring to the table. They're in an enviable financial situation right now and even if they don't use their cap room to sign a high-priced free agent this summer, their core team is still damn good. Presti can choose to find the "missing piece" this summer or just let his young players develop and go from there. I don't think he's fearing that he'll have to sign all of them to big contracts--I think he's more worried about some of them not becoming big contract players (i.e. stars)
They only have $46 million in committed salaries after this season and that includes Krstic exercising his player option. So that basically leaves them with about $7-$8 under the assumed $54 million cap, enough to get them a decent player.