No. If a multi-billion dollar company completely overturned its revenue model, it wouldn't be the same company anymore. And the billions of people who have used their services for years wouldn't be happy with suddenly having to pay. Can some subscription services work for some people and some products some of the time? Sure. But Google has so many services, coming to so many people for free, and making them so much money from ads, that even the hypothetical is ridiculous.