My plan is to have a plan...how's that!?
Seriously, the human body is pretty amazing. It does age and gets to the "nope, I just can't do THAT anymore" stage.
However, if you take your take in working up to weights and LISTEN to your body when somethin' ain't right...I think you'll have plenty of years in your shoulders barring an unrelated disease or injury. Work up slow, and drop down anytime you even *think* you might need to.
Powerlifting is pretty harsh on the body, and you can usually tell who's been doing thinks the smart way by how long they last.
I'd like to have a bow below my hunting weight, at my hunting weight and one a few pounds heavier. Shoot the heavy one every couple days until it's no longer heavy. Shoot the light one if things aren't feeling right or if I want to focus on release and have my "real" weight for everything else. This way I'll be "growing into" a bow without always shooting too much and also have one to fall back to on the days or months when something aint right.
Well, that's my plan at least.