Distributors entering Flatpakland

That "immutable core" thing does not automatically mean that it stays frozen. E.g. in Fedora Silverblue I get updates pretty much on the same schedule that I would get with the traditional rpm+dnf based Fedora Workstation. It does mean that making changes takes some more effort because the normal way to get the updated environment is to build it alongside the current one and the reboot there.

What is nice is that building the updated core environment does not require changing the current one. If the newly booted new environment shows regressions compared to the old one, I can reboot back into the previous environment.