I'm of the opinion that while there may be changes, the impact for most skis, of even a couple of hundred days of use, has little practical impact. But I have no more empirical evidence to support my opinion than anyone else.
That's why I'm asking if there's some reasonably rigorous study that's been done that shows something better than simply anecdotal evidence supported by vigorous opinion. Everyone's got an opinion - and lots of them are obviously wrong. [I'll admit, it's certainly possible mine are wrong in this case.]
IMO, the best way to know for sure is to perform some objective measurements.
My searches turn up little other than a claim that one of the Elan SCX ski designers claimed, as a result of measurements he made, that loss of camber and torsional rigidity was almost exclusively from removal of edge material from base grinds. [i.e. The metal edges.]
Make of that what you will. I'm guessing it's going to be a lot of days before a ski, especially with a stout core [not foam, for example] and metal is going to suffer severe loss of performance. Most [probably all] of us will have long moved on to shinier toys long before they're "worn out."