Like it or not, Google is probably paying around a million $$ a year to keep senior full-time developers around that want to work on the language. That could be used as a benchmark to calculate how much of an investment is required to have a healthy development cycle. If a community-maintained fork is created, it would need time and monetary investment similar to what google is doing just to maintain and develop non-…
If the popularity of the language grows enough, there will inevitably be new companies and ecosystems reliant on it and those interests may eventually band together to create forks they think bring value to their businesses.
Outside of that formula, forks will almost always remain niche and without significant investment.