Oh, I didn't read your post properly. For some reason I thought you were talking about routes opening due to sea level rising.
The northern sea route is not given the same scrutiny as the strait in that video though. Clearly if western allies were blockading China's sea trade at choke points, the sea route has some fairly obvious problems.
It's the defensible inland routes which will be the most important. To that end, the push to expand NATO into Ukraine almost could not have gone better for China if they had orchestrated it.
https://www.youtube.com/watch?v=ISHHe1Hu6d4
Skim this video, it shows slowly and clearly the potential change of routes.