They'd need to make a "developer version" of OS X, which would just be OS X with this hypothetical super-Gatekeeper shut off. Then the whole thing just gets silly.
I believe the PC will remain a PC. Take away its nature and you might as well just hand everyone an iPad.
I can see them changing the language around the various Gatekeeper options and adding additional "are you sure?" warnings to scare people off the allow everything option and unsigned / non-Mac App Store installations but I don't think it will go any further than that.
I believe the PC will remain a PC. Take away its nature and you might as well just hand everyone an iPad.