30K packages in Debian, nearly 20 years after it was first released. I know many apps are broken into multiple packages. By contrast, Apple's & Google's app stores have ~700K apps each, less than five years after they started. I don't believe Debian could handle that kind of scaling.

I have given this thought. My issue with the current model is that, because packages tend to be several months out of date, third parties increasingly point users to their own installers or packages instead of those in the repos. MongoDB and Google Chrome are two examples. Besides making installation more awkward, this dilutes the security value of having the repository in the first place. The repository model only provides security if users don't need to install things outside it.

I want to keep the centralised repository/app store with security guarantees - I think that's valuable for most users. But the responsibility for handling packaging and updating applications needs to shift from the distro to the application developers. This is only for applications, though: system components - core libraries, runtimes, window managers etc. - should still be managed cohesively by the distribution.