I wish they were leaving it as a par-5. Like 7,600 yards isn't tough enough.
According to Google Earth there's a cart path between a couple of the tees that makes it impossible to play the hole between 495 and 520 yards - you have to be either shorter or longer (at least to the middle of the green).
From the 520+ tee, a good teeshot for most players will skirt the end of the last left bunker. It looks like an awkward shape to get the ball in the fairway given that the real landing area is about 50 yards further back.
From the 490 tee, none of the bunkers should be in play.
IIRC most converted par-4's aren't shortened very much from their par-5 tees: 520 par-5 becomes 495 par-4 in most cases. One that is shortened a lot is 17 at Olympic (from about 530 to 470), but the landing area is basically the same anywhere on that hole. However, that is not the case with 18 at TPS - the landing area as a par-4 looks awkward, and very difficult.