A qualifying offer is 125% of the player's salary for the previous year or the minimum salary plus $200K (whichever is greater). His first-year salary was reported to be $1.2M, so the qualifying offer should be about $1.5M. A restricted free agent can field offers from other teams, but the original team has the right to match any offers.
It's very possible that another team will make an offer that the Spurs won't be able to match and stay under the salary cap, but there's a good chance that something could be worked out for the big guy to stay. The team and the fans love him, and by all accounts, he loves playing for the Spurs, and has said he wants to keep working with the Spurs coaches to keep improving his game. Here's hoping he stays.
As expected.
It's going to be interesting to see if he does get a big offer from someone else.