Well, the Carbon team primarily focusses on one customer: Google. If management decides "it's carbon now" then a few thousand developers will write carbon or change jobs. If they are then somewhat successful inside Google, people leaving will spread it.

I don't think it will reach the same distribution as other languages, as the niche is "large C++ projects, which want to transition to something else without rewrite" for anybody else there are a huge number of alternatives.