You probably could get a team with capspace to take Calderon this summer. He's easily still a very good veteran point guard to have, a coach's pick type, and with so many teams have massive amounts of capspace, a salary dump will be quite easy. I think we'd be able to get a 2nd round pick even. However I'd only do that if I got verbal agreements from free agents.
Durant isn't coming to a lottery team with a prime star in decline. Melo is being paid 25, 27, 28 million over the next 3 years and he's not shown great health or value as a player. He's far better off sticking with Westbrook.
I do think we can make a great case for the advantages - one being that if you add him to the roster instead of Afflalo/Calderon, with Galloway/Grant as PG's, you're likely the 2nd best team in the East. In the East with KD added to Melo/KP in NY, we'd be in line to make a Finals run right away. In the West, got to go through Golden State, San Antonio, Clippers. Been hard for them. Since Harden left, they haven't been back to the Finals. Then you could make a case of being the next Pippen/Jordan with Melo/KD. Another case, NY market and being the man in NY - bringing success back here what it does for you. Next up, KP. Porzingis is only scratching the potential of what he can do. Finally, Fisher. He has a great relationship with Fish. Trust with a coach. What would Jordan and Kobe be without Triangle culture and Phil Jackson? Ringless possibly.
I see it as a long shot, unlikely. We should definitely go all out and try though. The killer for us is the standings. Even though NY is much improved, we're in a tough spot to make the playoffs. Durant isn't going to feel all giddy about joining a team that won 36-40 games, finished 10th in the East from being 3rd in the West and having won 55 games. No matter what he thinks of Porzingis, Phil, and Fisher I don't see him making that jump.
I do think he would be great great fit in the Triangle. Everything that is wrong with his pairing with Westbrook is solved with what is done with the Triangle. And defensively, the versatility of having Porzingis, Durant and Melo up front with Grant and Galloway in the back, would be something.