They did change it again.
For cruise ships, if you embark and disembark at the exact "same" US port, no matter where the ship goes, you will not need a passport to reenter the US. An ID card and birth certificate is all you'll need.
But, if you embark and disembark at "different" US ports, you will need a passport. This means a repositioning cruise.
As always, embarking and disembarking in different countries will require a passport, as it is today.