It's not that great unless it's required. For example, the bare "sqlite3" package name will always sound official/canonical next to "@JoshuaWise/sqlite3" and people will forever accidentally install it even though they want a scope. Just like how users type in domain.com when they really wanted domain.org.
Did you think nothing can be improved upon Java?
The Java space, Maven, more precisely, did come up with the first namespaces package repository. For some reason other package managers don't do it, for simplicity I guess, and it always come back to bite them in the butt.
For reference, Maven 1 didn't have groupIds, Maven 2 added them. They did it for a reason and that was back in 2005!
I'm having the exact problem you're describing in a macOS app, where an app that was previously name.janedoe.app is now org.company.app. What a mess that caused.
Github has some good examples of this when repos change hands.
If it's feasible to do so, you also push updates to both namespaces for a little while during the transition.
For example, instead of having to push updates to both packages, you push updates to the new one and, because you've annotated the old one with the move, users have a somewhat seamless experience when they run their update: they'll get a little heads up about the move, explain that oldpackage eol'd at 5.4 and newpackage picked up at 6.0, and would you like me auto-update your manifest?
And/or the package manager supports a rename flow that does this for you.
It doesn't really work until FQN is required by all.
Elm got this right. You shouldn't have to be clever in thinking of a package name just because the obvious one was taken and you have a different flavor to offer.
Rust didn't and it's another ecosystem where people feel the need to squat on names or suffix a '2' when they think they've written a better library, just like NPM.