Depends on the book. If the book is less valuable then membership costs yes, else people might make a business out of selling overdue books.
How many books can you sign out at once? Like five or something? You think people are going to make a business out of selling five books on a street corner? How much do you think they’ll fetch given they’re already free at the library?
Lunacy.
This is solely about eliminating late fees.
If someone is going to be stealing books from the library and selling them under the new system, the incentives to do that would be exactly the same as under the old system.