> I'm somewhat surprised nobody has packaged up an old version and wrapped it with "only run flash for these urls" and "don't update the ppapi plugin" type functionality. All the pieces seem to be available: https://support.google.com/chrome/a/answer/7084871?hl=en
This is likely to be of minimal use, since browsers will soon be removing Flash support entirely. Firefox in particular is carrying a significant amount of code to shim gtk2 in a gtk3 program.