Flathub aims to be the place to get and distribute apps for Linux. It is powered by Flatpak which allows Flathub apps to run on almost any Linux distribution.
How does it stack up against traditional package management and others like AUR and Nix?
Its a solution to one of the typical Linux issues. Its a step toward overcaming the fragmentation of Linux package managers.
I don't personally like it too much, I prefer the distro package stuff, but I understand the app developers cannot manage a plethora of different package formats.
Distro maintainters should, but its clearly more and more a massive task for different distros to keep up with the amount of apps out there.
Also, npm, pip and the various "packaging" ways existing add to the chaos.
I see distro package managers converge toward providing basic packages for the general system and some other solution like flatpack to provide additional stuff.
I think it would be wrong for flatpack/containers to replace package managers as well, it's not their scope.
I see distro package managers converge toward providing basic packages for the general system and some other solution like flatpack to provide additional stuff.
IMHO doing this would be suicide for most distros.
There are only so many ways you can make a basic system and the distro scene is already saturated by various interpretations of "basic".
A distro needs to offer more than the basic system and a huge part of that added value lies in its packages (and by extension package manager).