Re: ordinary distros won't have a package manager at all
Yes, I do.
ChromeOS is a closed box. You *can* install apps -- my single ChromeOS Flex machine has Firefox on it, just because -- but you have to know what you are doing.
But if Fedora Silverblue or Ubuntu Core eventually mutate into some kind of immutable-root-filesystem, largely bomb-proof end-user Linux, then yes, I think they will adopt the good bits of ChromeOS' design:
• dual redundant root FSs, because disk space is cheap now;
• a largely lid-welded-shut sealed-down OS design, with a read-only root FS;
• just the bare essential core tools provided: a minimal desktop, a web browser, a file manager with a few file viewers, and a shell.
As simple as it can be while being generally useful.
But my bet is that they will leave open some kind of cross-distro containerised app-distribution format, which ChromeOS does not have.
And the result will do all most end users need, it won't be very customisable, but it will be largely bulletproof. You will be able to pull the battery in the middle of a file transfer, or an OS upgrade, and when you turn it back on, it will resume exactly where it was.
And that will be a good thing for most people most of the time.
There will still be some oddball Linux distros out there that do things the old-fashioned way, and there will still be the BSDs.
Maybe Minix 3 will sort out SMP and subsume NetBSD.
Maybe someone will work out some kind of ML-powered code-auditing tool and be able to automate OpenBSD's code-checking, and it will merge with FreeBSD and DragonflyBSD as the last modern continuing scion of original UNIX™.
Or maybe, perhaps most likely, we will all end up running CollapseOS or FreeDOS, with the survivors of humanity living at the poles, as the rest of the planet is uninhabitable.