Actually, this was was part of the entire point behind the creation of copyright law. In the US, the 'for a limited' clause was there so that the author could benefit by monetizing a short term monopoly on their work, and then the copyright would expire and it would revert into the public domain.
Of course, this was in the days of hand written scribes and latter of movable type presses. The concept of digital information transmission did not yet exist, nor with it the idea that information could be shared near instantly at a fraction of the cost.
Since then, copyright laws have increased in duration from the original 'Statute of Anne' which provided 14 years, with an additional 14 years of the copyright was renewed. Compared to the current US version which protects from 70 years after the death of the author, or for corporate owned works, 120 years after creation or 95 years after publication.
We've also moved away from the publication of plain text works, to the new age of computer binary code. So even if the copyright on a computer program would expire, there are no provisions that the author need also provide the original source code. So the US copyright on Lineage should expire in 2093 (should no further extensions be added, and NCSoft is South Korean, so foreign copyrights can get even tricker) then we would be freely able to distribute the compiled client code... but without access to the never published source code or server software... well, doubtless 95 year old software would only be of any interest to historians anyways. Who could freely view the copyright code all that wanted, even during the duration of the copyright... just as long as they didn't distribute it amongst themselves for study.