On a recent project I deployed my Diazo resources to Firebase hosting, I'm still ironing out the perfect workflow.
In my rules file I then have something like this:
<theme href="https://mysite-c1ab4.firebaseapp.com/" />
And I ensure that plone.app.theming is configured to read from the network.
Having my theme resources managed by Firebase allows me to further decouple the design work from the Plone dev work.
I plan to refine my workflow a bit more, it should be possible to push the theme to git and then have a CI task do the Firebase deploy. Other things that might be good would be bench-marking to see if there is impact on site performance. The one site that I've used this approach on feels faster (but it also coincides with upgrading to Plone 5 so I can't say at this point).
Anyone using a similar approach?