I've heard this argument often, and I still don't understand it. What reason would they have to choose to forbid unsigned apps? It's like saying "we are to face a possibility that Apple will not allow any apps to run, and all apps will have to be web apps accessed by the built-in browser". Technically they could make those changes to the OS, but why on earth would they?
While you could argue this is similar to what they did with iOS, I think the author points out why that was done:
>Well, the third option that you stop doing anything useful with your Mac, only using it to browse the net, consume media content and read books...
iOS devices were limited for that reason, they weren't meant for what the author describes as "actual work". If you want to do "actual work", you buy a Mac, not an iPhone/Pad, etc. Arguing that Apple would move to a signed-only experience is essentially arguing that they would sell only iOS devices.
Look at their history, there has been a gradual trend in the app store from free-for-all to sandboxing, and now code signing is moving beyond the App Store. The question is why would they stop their current trend?
> Arguing that Apple would move to a signed-only experience is essentially arguing that they would sell only iOS devices
I think it is highly likely that in the future Apple will only sell iOS devices. Look at the XServe, a profitable product line killed off solely because it didn't fit in with Apple's strategy of mobile media consumption.
"apt-get update && apt-get upgrade" in a cron and I can get on with working. Hardly painstaking. Updates on OS X are more annoying, I've found, with constant restarts.