Commodification, I suspect. Based on the Google-cars I see traveling my Palo Alto neighborhood each day, my hunch is that the product itself is polished and the technical challenges well-understood, which means pricey tech leadership is no longer needed.
If other IoT products are a guide, once a legacy mass market product overcomes the technical challenge of getting connected, the engineering magic is done. We're then left with the grind of production efficiencies, regulatory hurdles, and finding traction with go-to-market strategies and dealer economics.
Sure, the IoT world is going to be a tectonic shift in how we live, but those shifts aren't always earthquakes.
To add to that, Google brought in an auto industry veteran, John Krafcik, as CEO of the division. Krafcik was previously the CEO of Hyundai USA, so he knows how to make an automotive firm profitable. “If I can find another project that turns into an obsession and becomes something more, I will consider myself twice lucky,” said Urmson on his Medium page. Jiajun Zhu, a principle software engineer and founder of the self-driving unit, is moving to a startup. Dave Ferguson, a machine learning lead, is also reportedly leaving, though his LinkedIn hasn’t been updated.
http://readwrite.com/2016/08/08/google-self-driving-cto-departure-tl4/