By 'wear-out' i assume you mean no longer functional...?
Well, with normal use - maybe three or four 'on-off' cycles per day (assuming pro-togger useage)...
Years...and years...and years...and years...
You will literally die before this becomes an issue with any camera bought this century...or last century for that matter...
This doesn't include damaged mounts from ham-fisted gorillas abusing their kit - just normal wear-and-tear from someone properly concerned with their equipment...
Plus: Mounts tend to chrome-plated brass (on the lens) and stainless-steel (on the camera) - not aluminium, as this would corrode and lock the lens onto the body...