Abolishing copyright will remove copyleft as well. Careful what you wish for; it might just become a pre free software world with all source carefully locked away from the public eye.
Someone should make a movie about a world without copyright.
We don’t need copyleft in a world without copyright.
I don't think that that's a realistic fear, though; this is basically already how it works with FOSS code being used in remotely-hosted SaaS systems and there being no effective legal recourse for FOSS authors.
It just doesn't officially say it yet in a law.