In Mac OS X is the new Classic, I made some bold predictions about Apple’s operating system future, but forgot to attach some sort of deadline to these predictions. Allow me to repair this omission here by adding this: I believe Apple will announce to developers the operating system transition described in that blog post within the next five years, at WWDC 2018 at the latest. So if WWDC 2018 comes and goes and no such thing has been announced, you are free to point and laugh at me.
On the same subject, I omitted that not only I believe that Apple will allow Developer ID apps on desktop iOS, but I believe Apple will in fact allow distributions of desktop iOS apps without requiring developers to pay Apple for that privilege (either through a free certificate or no certificate needed at all), though, like with Mac OS X Mountain Lion currently, the default setting will likely not allow running such apps. This is in consistency with what I already expressed in my blog post about Developer ID.
Lastly, for those of you wondering, I finally remembered an example of behavior that apps ported to Mac OS X could technically get away with, but ended up “sticking out” among native apps including to the user base: drawing directly to the screen outside of full-screen mode. At the start of Mac OS X some games would do so, even in windowed mode, but it ended up being noticed, as it resulted in ugly interactions with the transparent on-screen volume and brightness change overlays, and then very bad interactions with Exposé; so as a result developers were pressured not to do so and by the time of Mac OS X 10.4 Tiger pretty much no newly released app was drawing directly to the screen. So the same way, Apple would not even need to mandate all aspects of what a good iOS desktop app would be, they can allow some things that are not completely iOS-like to allow developers to more easily port their apps, knowing that over time the community will ostracize such exceptions.