Sentry started life in 2008 as an unlicensed, 71-line Django plugin. The next year we began publishing it under BSD-3, and ten years later…
Sentry has moved to a new license for its products called Functional Source License, and explains in this article the story of the licensing for these products and why they throw BSL for FSL.
FSL is better than strait proprietary and if a company had to choose between the two I hope they choose FSL. All that said it just doesn't feel like there is a real hope here for the eventual Open source fork here. It's just a fail safe for people still on legacy systems and even then 2 years of potentially no new updates ... Could be killer for security flaws. With tons of paradigm shifts between then too.
It almost needs a SLA that says if it isn't maintained to a certain level then it is also opensourced.