The idea that there would be no more creative works without copyright is pretty obviously false for music (so many people enjoy making music that the only way it could disappear is if we evolve to no longer have ears, and even then it will probably exist in the form of deep bass that you can feel), and most likely false even for things like movies and video games. It may be the case that high budget works become extremely rare, but things like short films would continue to exist, and the existence of things like Spring or various total conversion mods show that even video games would continue. It is definitely false for things like business software, where people will pay for professional services to make their business more efficient.
On the other hand, there are plenty of interesting creative works (e.g. mashups) that are illegal today, and obviously they're being made without monetization. With new tools we even have people making things like Plankton from Spongebob singing Tool songs[0]. There would still be plenty of creativity in the world without copyright.
It's not obvious that we should prioritize the ability to easily fund high budget works over the ability of people to freely share their remixes and mashups, for example.
On the other hand, there are plenty of interesting creative works (e.g. mashups) that are illegal today, and obviously they're being made without monetization. With new tools we even have people making things like Plankton from Spongebob singing Tool songs[0]. There would still be plenty of creativity in the world without copyright.
It's not obvious that we should prioritize the ability to easily fund high budget works over the ability of people to freely share their remixes and mashups, for example.
[0] https://www.youtube.com/watch?v=14yO95OVsLE