Great article. We built https://github.com/CanopyTax/single-spa as a solution to front-end micro-SPAs. We initially approached the problem from the perspective of wanting to migrate away from an angular 1 SPA. Since then we have evolved into fully embracing micro-SPAs. Single-spa has been in prod at https://canopytax.com for over a year now. We have over 10 micro apps that are loaded on demand. Our loading mechanism is a SystemJS plugin called sofe (https://github.com/CanopyTax/sofe)