Google is in between the proverbial rock and hard place, they have to grow in order to survive, being a monopoly means nothing (think greyhound bus) to the market, the only thing that matters is sequential revenue growth, that means new markets, new products, new anything that makes money. With CPC declining the only short term fix is to max out revenue per query, squeeze more out of those serps.
They are also running big burn rates in other areas, handing out tablets and laptops at cost, building out fiber networks, etc. in an attempt to gain a foothold into the future. The only thing allowing that burn rate is ad revenue. I expect them over the medium term to further amplify their ad layer, SERPs at this stage of their game are nearly irrelevant to them, a bit of window dressing maybe but not the foundational product it once was. It is a monetization game now, the query must be monetized at all costs. I believe they take their traffic/market share for granted now and maybe they are right. Maybe not, time will tell.