@bmeck has some amazing work close to landing that introduces ESM modules to node:

nodejs/node#14369

Our strategy for hooking require statements (using require.extensions) will no longer work for .mjs files (which use the new ESM module syntax). @bmeck indicates that we might be able to pull off something similar using import()

Let's try to stay in the loop, and make sure we have an implementation ready to go for .mjs as soon as it's possible.