You know its funny, I've never heard of distrobox or toolbox, but I do know of NixOS and I do think flakes are the future purely because it actually installs on the system.

Actually, I get the impression that docker containers are gonna see more package adoption than snap and flatpak and appimage (and to be even more clear for the exact usecase those things are trying to offer)

But like everyone who tries a hand at the crystal ball I could be wrong. Probably pretty easy to guess that the Ruby enjoyer could be wrong about software stack adoption.