After the draft, I think Spurs will have 3 priorities in FA:
Priority #1: Getting a quality bigman.
Tiago Splitter will be option A, B and C to fill that need. If Spurs can't reach a deal with them, they should go after a vet FA with the MLE.
Priority #2:: Getting a backup SF.
Spurs will have 5 perimeter players under guaranteed contracts (Parker, Hill, Ginobili, Anderson and Jefferson) and 4 ones with partially or fully non guaranteed contracts (Jerrells, Hairston, Gee and Temple). Among these 9 players, only 1 is higher than 6'6". Spurs will need a player with some length. Outside shot and good defense will also be welcome.
Priority #3: Getting a 5th bigman.
Duncan, Splitter, McDyess and Blair should be a good rotation for the playoffs but Spurs will need more depth for the regular season to have fresh Duncan and Dice for the playoffs. There are dozen of options for that spot but Spurs could go with re-signing Bonner

or re-signing Mahinmi

.
I can Spurs going with this 12 players active roster at the start of the season:
Parker, Hill, Ginobili, Anderson, Jefferson, backup SF, Duncan, Blair, Splitter, McDyess, 5th PF/C, one of Temple/Gee/Hairston.