I remember last year - or even earlier - someone from Google mentioning to the press they were considering an evolutionary change. This was something that might take years to accomplish, and that during the development they might have to sacrifice some of the quality they had developed. But they also said that in the longer arc of things they thought it was the best direction. Imagine that - thinking beyond quarter-to-quarter!
I don't remember if that comment came from Matt or Amit or even someone higher up. However, I took notice of the storm warning at the time and now it seems the storm is on us. The overall algorithm is doing things that we can barely describe, to say nothing of reverse-engineering. And updates are so frequent that we can't even identify the date of minor ones.