My uneducated opinion on the issue is that Flash would've prospered on mobile phones if Adobe weren't greedy ****s and allowed free-to-download flash players for mobile devices, instead of charging licensing fees for each phone.

If Adobe can make money off of Flash on desktops with free-to-download clients, they could've done the same thing with mobile devices. If they hadn't done that I'm pretty confident that Flash on mobile phones would've been far more succesful.