#1 and #2 make sense. I could legitimately see KG retiring and doing the franchise a favor by forgoing his remaining salary. Waiving Pierce makes sense if KG retires.
As for Bass/Terry, I'd rather trade them for expiring contracts now, or non-guaranteed deals in the off-season, as a way of clearing their salary.
Terry shouldn't be too difficult to move despite his bad play this year. He has a proven history of being a valuable playoff contributer, and I'd imagine some "contender" out there would desire his service.
Bass, on the other hand, may be much more difficult to move. Players like him are a dime-a-dozen. using the stretch provision on him may be the only way to clear his salary.