As for 99% in your institution etc, as I said it doesn't matter most of the time, as there is already a more capable OS available.
Only because said institution still buys a giant fleet of laptops for the staff and refreshes them every 3 years. I can't remember the figure on our total spend for devices each year but it's certainly in the double digit millions. Eventually I don't think they're going to do that.
And as a laptop replacement on the go, you need a laptop dock, which more "inconvenient" than an actual laptop.
Sure, but as this stuff becomes more mature and possible, institutions are going to wonder whose work truly requires a computer on the go, because buying them a laptop rather than just getting them to use their work phone on a dock at their desk will be more expensive. As I said, every desk at the multiple locations at my institution has a USB-C dock and monitors already.
People who actually need a computer on the go will still get a laptop, but I'm not so sure about the rest.
As for replacing a broken laptop, yes, it's part of "in a pinch" and it's still a partial replacement.
The issue I have is when someone says "I could replace a 3.5 pounds laptop" with a phone. No, you would still need additional hardware on the go and on site you probably already have desktops available. And above all, there are all the missing software and features from a desktop OS.
It's not a given at all that there are desktops available. I work for a large institution with thousands of staff, thousands of desks, and at this point 99% of desks have a USB-C dock and two monitors, that staff plug their laptop into. Only edge cases get a desktop. And I've already heard we're keeping a close eye on this phone-as-desktop stuff, because no organisation wants to spend money on laptops they don't need. We've virtualised the majority of the apps we use and they can already be run from any platform.
It's not there yet, but could be eventually.
And for the last point, I am the first person to ask for a 2lb MacBook. I refuse to buy any Apple Silicon MacBook over 1kg. I have 2 12" Macbooks and I still use them daily. Plus a 2lb cellular Thinkpad. So I am the first fan of ultraportables.
Dex or Stage Manager in a phone are no replacement for that.
Not for me and you, but for many people, it could be. I chase the best setup rather than the minimal acceptable setup. Phone-as-desktop is probably going to be that minimal acceptable setup that I'll only ever use in a pinch.