Dude, the Spurs will have the Full MLE to throw at Boban and its going to be over 7mil for next season as its based on the % of the Salary Cap (projected to go up to 85-90 mil next year. Spurs can resign Bonner and Butler for the Vet min no matter if there over the cap. With Boban, West (PO more than likely opting out), Bonner, Butler, Ray all coming off the books, the Spurs will be just a tad under 80mil. Let's say the cap is 87mil next year. Spurs can use the 7+ to split between West and Ray, upping their salaries. Bonner and Butler, if they return, will be signed for the Vet Min. Spurs will have the Full MLE to sign Boban, which should be over 7mil a year.
Spurs have more than enough to retain the entire next season. Spurs will more than likely use their MLE to retain Boban. West and Duncan aren't going to be playing forever.