That's a good summary of why Google has been so successful.
They have a way of making engineers and regular people really excited about their projects. It's a feedback loop - have exciting stuff, recruit smarter people, work on more exciting stuff.
Take away Glass, self driving cars, Loon, and all the other blue sky projects, and you still have a wildly successful company. But take away those two cash cows and Google is broke.
On the other hand there is no telling what sorts of massive successes will come out of Google. They will have their stakes in any mass-produced self-driving car, Google Glass is at least going somewhere, and Android is already very popular and enabling Google to get Ad revenue without being fought by Apple every inch of their way.
The stock price and market capitalization is driven both by current revenue but more so by these insane projects and the probability that there will be another big success.