Would you keep paying for Google Ads if they didn't deliver any sales? If so, would you keep paying them as much or more than you are now?

I don't think it's such a crazy idea that people would find (or create) alternative if the vaule was not there.

It doesn't really matter, as it's unlikely that any ad blocker is going to become so widespread that it takes down Google's entire business model, especially when they control the majoritiy of the people's web browsers... 

 I've seen google ads work like magic in a couple of businesses I've worlked for. The return on the investment was totally worth it. Having a google ads budget and team working on it is a no brainer. If we kill google ads and don't provide something extremely effective right away many businesses would suffer.