I haven't the slightest clue what you're taking about. You can change your license on future versions, but you can't retroactively change the conditions of an offer that's already been accepted.

If you're talking about the ability to delete published packages from NPM, that's entirely unrelated to licensing.

Yes, you can.

In order to be a legally binding contract, three things are required: an offer, acceptance, and consideration. Consideration is the value gained by entrants into a contract.

In short, if you did not pay to license some piece of open source software, there is no consideration for the author of that software. Hence, the license attached to the software is NOT a contract binding on the author. It is a bare license -- simply the terms under which you are permitted to use the author's IP -- and the author is legally entitled to revoke it at any time.

You may not like it, and it has unfortunate implications for open source, but that's how contract law in common law jurisdictions like the USA works.

https://lulz.com/linux-devs-threaten-killswitch-coc-controve...

Some Linux contributors threatened it after the CoC was instituted, but nothing came of it.

Do you have an example of somebody actually revoking copyright and successfully suing or settling?

This same guy actually did try revoking the license to his open source slot machine game from the GeekFeminism contributors, and the GF people were like "okay, yeah, sure, whatever, we promise not to touch your shitty game again".

So this remains untested in court.

But if you actually look at the relevant bits of contract law, you'll see... he actually has stopped-clock syndrome on this, and it really has dire consequences for how we do open source. At least in the USA, and admittedly, different views on copyrights and licensing prevail outside the USA, where much of the work on Linux is done.