Memes

Technically the idea is that if Chrome has barely any market share (will never happen, but let's pretend), they cannot implement this as it will anger and lock too many users out of day to day life.

However...

With Google Search and YouTube being by far the most 2 popular websites in the world, I think they still could. The vast majority of people would never give those up and if they're told to use another program to access them, they absolutely will, meaning in an ideal world with a browser competition, they can easily destroy it immediately.