Will Flatpak and Snap replace desktop Linux native apps?

Probably unpopular opinion: I hope that happens sooner than later.

I always saw packaging every piece of software for every distribution as a lot of duplicate work that could be better used somewhere else.

As an example, Gentoo's default repository has 18k packages (not to mention the many other packages in additional repositories), each one of them with its own building script, maintainers and tests.
Most of those packages are also present in other Linux distributions, again with their own maintainers, different building scripts and having passed their own tests.

Doesn't that sound like a lot of duplicated work for each distribution that could be used instead on improving the core system and pushing the burden of packaging applications upstream as flatpaks?

Also, since flatpak packages dependencies with the application, they could fix the dependency hell problem in a big part because the developer will determine what dependencies your package runs with, instead of relying on whatever version of the dependencies may be installed in your system.

And it could also solve the quick death of Linux applications. I'm sure most of you saw how quickly applications get unusable in Linux. You find an application you like, but because it was developed for an older version of some library (like OpenAL or GTK+2) you cannot use it anymore.
Have you seen that in Windows? You can still use most of the applications developed for Windows XP in Windows 10.

That of course has its drawbacks. Because you are packaging dependencies with the application, you will have duplicates of the same library for each application, but I think that's a fair price to pay for more stable and durable applications. That's very similar to what Windows applications do.

I'm talking about flatpak. Like most of the people here, my experiences with snap were bad, I am not interested in it and I think it's Cannonical going their own way.