I'd be surprised that people would just turn that feature off pretty quickly after getting a new Mac. There are tons of application out there that aren't sign and aren't malware. People will come to view this feature like the annoying warning about bad SSL certs.
Hm, that's a good point: "warning fatigue" that users get. I hadn't thought about it from that point of view; I guess how fatiguing it is will really depend on how quickly developers in general get aboard the "sign your application" train, so I'd be curious to see the response from the legions of independent Mac software developers that aren't using the App Store for delivery.
Most people don't install tons of apps (and many of those who do use the App Store). It's hard for me to think of seeing that dialogue once a week as onerous and I bet the vast majority of people don't install more than one app a week.
