The cap will probably rise a little bit, in my opinion, but not by enough for two max players -- you'd have to have almost all your roster expire for that to work out. Fitting one max in, especially someone coming off a rookie deal who's a restricted free agent, on the other hand, would be possible if Pierce and KG's contracts were jettisoned.
Still, I don't think Danny's interested in trading Pierce and KG merely for cap space next year. A mixture of young players and expirings, which would create roster flexibility, might be interesting to him, but he signed too many players to 3-4 year deals in the $5-9 million range last offseason to be counting on being able to unload enough of them.