Magnum was a great show for its time. Took risks that shows did not take in that era. Ended before its time because CBS would not give up on the Thursday night slot NBC was starting to dominate until the public had lost interest.
If you think about it, there is the CBS / Hawaii / Navy universe that still lives. While there was no linkage in producers, Magnum characters called the police "Five-0" and even "McGarrett" was referenced several times in the early part of the series. As you remember the show ended with Magnum rejoining the Navy. Same producers then did JAG, which why it never referenced Magnum directly, was very similar. From which came NCIS, from which came NCIS LA, and not H50 is back. A new Magnum, with the right actors could work.