Second, if the book lost copyright protection wouldn’t Donald, losing that revenue stream, then be motivated to replace it by writing a follow up book?
Artists should be able to benefit from their works, but your question implies (to me) that because a work is popular artists have a right to continue to profit. You ask if they should be “forced” to “give up their copyright”. I think it’s good to keep in mind that anything copyrighted is being withheld from society at large; that we collectively pay a tax to authors in the form of giving up our collective right to remix and recombine works and profit from them in turn.
Particularly in the modern world of effortless free duplication and distribution, that’s a heavy burden to pay and it makes no sense to me that we would collectively agree to pay it for many decades even after the original author is dead.