I think professionally, camera kit doesn't really devalue all that much.
Say I sell a $3000 camera second hand for $2000.
I've lost $1000, but I'm damn sure that when I'm upgrading a camera it'll make a significant enough difference to my business that that $1000 I've lost is peanuts compared to my profits.
The same idea follows for shutter replacements too.
I went from a rebel xti to a 7d. My 7d paid for itself, extra lenses, flashes, studio gear and my bills in the first year.
The only way I'd make a loss on it is if I paid someone to take it