Originally Posted by
2wheeladdict
... over time these pivots will develop play eventually preventing the derailleur from holding a shift.
The time span you are taking about is extremely long, however. Even in mountain biking, it takes years and tens of thousands of shifts in really crappy conditions to wear out the pivots on a derailer. You'll likely be on to another bike and a whole new shifter/derailer system before even the cheapest one wears out.