Hard cap.
Franchise tag.
Eliminate max salaries in the bargaining process.
Any steps along that path would be helpful. I.e., if you don't eliminate max salaries completely, at least substantially raise the amount. If you don't have a hard cap, at least make the penalties for going over the luxury tax really stiff (which they did a fair amount in the last CBA). If you don't have a franchise tag, maybe something sort of like that could be done, such as maybe giving the current team a salary tax discount for resigning their own players. Etc.