Grant:
KMM:

Electrically driven / assisted turbos (or for that matter electrically driven superchargers) can do what a traditional mechanically driven supercharger can't do, namely, spin up "in anticipation" of demand; i.e., ahead of engine speed.

Good point - should be interesting to try this technology

Looks like Porsche's sister companies are starting to show that technology roadmap with greater clarity:   http://www.autocar.co.uk/car-news/new-cars/audi-plots-new-petrol-electric-hybrid-powertrain-2017

The Bentley Bentayga has a 48 volt system for its active roll bar system; this is one of the first production applications in the Volkswagen Group.   Perhaps, a bit of 48 volt magic will be seen on the 991.2 Turbo.