I would strongly doubt there'll be any difference in penetration in the short-term. You may not be able to think of common use cases, or any at all, off the top

I would strongly doubt there'll be any difference in penetration in the short-term. You may not be able to think of common use cases, or any at all, off the top of the head, but over the course of a year, chances are you'll come across some interesting website or feature on the web that requires flash. And the barrier to viewing it (installing Flash yourself) is really not that high. If you want to test it without actually uninstalling flash, just install ClickToFlash (for Safari) and you'll see many sites even use flash for non-dynamic things like buttons.