You may need a top 10 and 20 player to really force Durant to consider the team. I'd try for more of a balanced team by looking at a top 10 guy and two 30ish players as I think Smart could be a 30ish after another season or two.
1. At draft or I believe more likely at this trade deadline try trade of Sully, Turner, AB, Mavs 1st, Cavs 1st, and 2016 Cs 1st, for Cousins(top 10 player at times).
We probably lose out on lotto and make playoffs if we do at deadline but Kings can tank to get Towns or Turner or whatever they trying for. Seems Cousins Era is done there.
2. The Draft. Assuming Cs have Cousins and make playoffs in bad East. Grab a solid athletic PF player say Cliff Alexander, Harrell or Portis with the Cs middle round pick. Clippers pick draft another decent big for depth (and Zeller insurance) in D.Johnson or Upshaw. With Philly pick take a backup SF like Jake Layman or one of the two decent SF Euros in the draft.
3. Sign Reggie Jackson(top 20 guy on a given night) also maybe inside line to recruiting KD.
2015
Jackson, Smart, Young, KO, Cousins
Pressey, Dawkins, Layman, Wallace, Cliff, Zeller, D.Johnson
2016
Jackson, Smart, Durant, KO, Cousins
Dawkins, Young, Layman, Cliff, Johnson, Zeller*
Smart, Young and Jackson's flexibility allow for some great rotations with Durant. Plenty of big man options to compete with any front court in the NBA.