If Spurs win all remaining games (5) they will have 70 wins and a 3-1 season advantage over the Dubs. If the Warriors only beat Memphis once that gives them 70 wins also but an inferior head to head against the Spurs.
Playoff Tie-Break Procedures (from NBA.com)
The following outlines the NBA's playoff tie-break rules and procedures based on the final regular season standings:
Tiebreaker Basis
(-) Tie breaker not needed (better overall winning percentage) Both 70
(1) Division leader wins tie from team not leading a division Both Division Winners
(2) Head-to-head won-lost percentage Spurs 3-1
(3) Division won-lost percentage
(4) Conference won-lost percentage
(5) W-L Percentage vs. Playoff teams, own conference
(6) W-L Percentage vs. Playoff teams, other conference
(7) Net Points, all games
For some reason I thought Spurs had 13 losses. They have 12.