My impression is that fashion, the real difficulties that exist in some cases, and -- particularly -- the absence of firm teaching of grammar and punctuation in school, are all leading to an accelerating decline in the correct use of the mark.
In my "Apostrophe News" entry of a week ago, I said that I hadn't seen anyone point out that the city council of Birmingham, England, was following in the footsteps of the U.S. Board on Geographic Names when it banished apostrophes from street signs. That's because I didn't read Michael Quinion's discussion of the flap as carefully as it deserved.
I couldn't agree more. If everybody understood the rules governing apostrophes, there would be less temptation to break them. If we didn't see the rules broken all the time, we'd find it easier to understand what the rules are, and apostrophes would be better able to do their job.