If intellectual property rights cease to exist, then there's no longer any legal basis to enforce the GPL and similar licenses and the Free Software ecosystem would collapse. Are you sure you want that?
EDIT: Replaced "open source" with "Free Software". My thanks to other posters for the correction. Yes, BSD-style open source would still survive.
I'm not sure what "share publicly" has to do with anything. GPL doesn't apply until you do share the software, and even then doesn't require you to do anything publicly.
Why is this? Because software is different from literature and visual arts. In a copyright-free world, once you copy a work of literature you have the whole work at your disposal to copy, modify and redistribute however you see fit. For music it's a bit different because you may need to reverse-engineer the music sheet, for example, but there's a lot you can do with just the recording of a piece of music.
With software, the only thing you could do is copying it, or try and modify the binary, because you still don't have the source code. Sure, you can reverse-engineer it (which is already legal in some situations in certain jurisdictions), but the software wouldn't be free in today's understanding of what many consider free software (i.e., software that respects the four freedoms outlined by the fsf). This means, you get your copy of, e.g., AutoCAD, but it would still be hard for you to modify it, because, despite the absence of copyright, you'd still have no way of getting source code to work on (unless someone leaks it).
So I'd say that, at least, absence of copyright wouldn't help with software. It will just create a situation where those who want to incorporate your source code into their products without publishing their source code will be able to do just that, and you'd have no recourse.
Right. And you can already refuse to accept a job if all the code you produce isn't open sourced. Good luck with that on most companies, though.
That being said, right to repair goes hand in hand with the abolition of IP to resolve these edge cases. The problem of not providing the manual to your distributed invention goes far beyond just intellectual property, and is largely an independent issue, but good right to repair legislation is all encompassing, and is a consumer protection that naturally fits with IP-less software as well.
I don't know about that. Most significant software packages require ongoing maintenance (bug fixes, security patches, compatibility with other software) and add new features over time. A one-time leak certainly would be damaging but not necessarily fatal since most businesses want to have assured support and upgrades.
And not to get sued into the ground.
After the leak, anyone can.
Prices would adapt to the reality, and the original vendor would have a hard time demanding the rates they are used to when suddenly faced with competition. Especially competition that kept changes open, which instills more confidence in consumers of the software.