There is no 80-year norm against redrawing borders. 80 years ago, Crimea was a part of the Russian SSR - now it's part of a free and independent Ukraine.

Eastern Europe looks a heck of a lot different, as did British India.

In all fairness, 80 years ago, the world was on the cusp of a massive border redraw, but the Phillipine Islands were still a US territory.