Publishing an ES6/ES2015 package to NPM

When I can, every javascript project I start makes use of the new ES2015 (or ES6) standard. The features (better classes, arrow functions, etc.) are just to good to ignore, and, using a transpiler such as Babel, code can be made compatible with older browsers and systems. For private projects the transpiler can be incorporated in to the build process. But, how do we proceed when we want to make a project public and usable by others?...