The main advantage for using "or later" is not really to be OK when a new version of the license is published, as this happens rarely. What you gain is the pos

The main advantage for using "or later" is not really to be OK when a new version of the license is published, as this happens rarely. What you gain is the possibility of combining this code with any other code that is under a later version of the license. If there is code X under GPL-2.0-only and code Y under GPL-3.0-only, these cannot be combined, since each license declares that any derivative work has to be under the same license. If code X were under GPL-2.0-or-later, the combination would be compliant.