Any alternative to showing videos on the web will obliterate the need for flash for pretty much all users, and it's hard to imagine any alternative actually being worse for that (but deciding on format sure seems tricky).
I didn't know until today that this spring's RSA hack used Flash:
Perhaps, but interestingly enough the attack wasn't against a web browser, but against Excel running a Flash applet. Maybe that path was chosen because it's less carefully examined by security policy and security software; I don't know.
In any case, it's certainly true that this pathway wouldn't have been available if not for the unnecessary use of Flash in places where it doesn't belong, i.e., Excel. Which ties into the theme here rather nicely; Flash used unnecessarily is worse than Flash eschewed entirely.