The 40,000 drivers won't go anywhere. They will just be using other comparable services.

I was using Wheely before Uber came to London. I switched to Uber after multiple unpleasant experiences, like the drivers showing up 40min early and chasing me. But Uber didn't invent this concept, it just happened to have become the platform that dominated the other ones through its critical mass / network effects. But it can be replaced pretty quickly.