Flash didn't disappear when internet technologies got better. Flash disappeared because Apple refused to distribute it on iPhone - partly because Adobe couldn't effectively shrink it down to early generation iPhone technical capabilities - but partly because they didn't want a competitor to the iOS SDK.

Then Apple effectively vetoed - explicitly and through lack of investment) futher improvement in audiovisual web platform technologies (e.g. the custom shaders that Adobe wanted to make part of the nextgen filter spec) during the critical period where developers were making their platform choice for mobile.

Apple has been no friend to the further evolution of the web.