People will learn to press all the buttons with scarry messages to ignore the wrong certificates. It may be a problem for credit cards and online shopping.
replyHSTS was specifically designed to block you from having any ignore buttons. (And Firefox refuses to implement a way to bypass it.)
replyBut this is also why the current PKI mindset is insane. The warnings are never truly about a security problem, and users have correctly learned the warnings are useless. The CA/B is accomplishing absolutely nothing for security and absolutely everything for centralized control and platform instability.