Niklas Berg has released his Phaser 3 + ES6 Bootstrap template: "This is based on the excellent Bootstrap project for Phaser 2 "Phaser + ES6 + Webpack". Most of this project is an exact copy of that repository, only with the Phaser package updated to Phaser 3 and the example replaced with one based on Phaser 3."
"I did this because I wanted ES6 and live reload. Can't live without it and I wanted to try out Phaser 3. The Phaser 3 example code is a bit of guess work since there are no documentation yet. Be warned, stuff might be broken and Phaser 3 is not ready for production yet. I'll accept any pull requests that seem reasonable, but I'd expect that someone more qualified will step up and create a better Bootstrap project in the months to come making this obsolete."