Even if they just land Durant, the rookie, and no one else, I think the Knicks are a top 5 level of team in the East next year especially if they can retain Jordan (which they may be able to do if they only get Durant and no other free agents).
I mean this team is probably better than Indiana and depending on Irving, Leonard, and Butler/Harris could be better than Boston, Toronto, and Philadelphianto (for the sake of discussion lets just give them Barrett).
PG - Smith, Ntkilina
SG - Knox, Trier
SF - Barrett
PF - Durant, Ellenson
C - Jordan, Robinson
Maybe you bring back some of the vets or some vets in free agency. That seems like a top 5 team in the East and one that still has plenty of assets to move for vets. That team in the playoffs with Durant leading the way and I could see a run to the finals as Durant has that special ability to carry a team on his back. I don't think they would get by Milwaukee (though they have their own free agent issues), but you never know, especially if other East contenders suffer free agency losses.