Dave Mark, writing at The Loop:
Interesting difference between the Mac and iOS is the ability to download and run a Mac app without any involvement from Apple. While you can sideload an iOS app using Apple’s Mobile Device Management, Test Flight, or by building the app yourself, none of those offer the freedom the Mac brings.
Will Marzipan change that, even a bit? Will I be able to download a Marzipan app from a developer’s site and just run it on my Mac? Or will Marzipan restrict apps to the Mac App Store?
I would bet good money that Marzipan apps are only available through the Mac App Store.