Anybody inventing AGI would be a big deal, but (1) don't hold your breath and (2) it could just as easily be a negative for Google and for the rest of us.
And their core goal of truly autonomous vehicles is a technical challenge that at this point seems like it will take at least several years more than what they originally thought 3 years ago. Their situation is not similar to FB in 2008 at all.
Even if they overcome this the bigger question is whether the market opportunity is worth the R&D costs, and whether or not bulky self driving vehicles are the best and most lucrative solution to mass transit.
Speaking of market opportunity, are there SDVs being tested in outside of California and Arizona? The rest of the US gets its fair share of rain, snow, and ice. Even if the Bay Area can manage self-driving cars, when would we expect a rollout in places like Minneapolis or Boston?