It would be a monumental effort for smaller browsers to keep chromium extensions working, while the rest of the ecosystem moves to the new APIs. The only way that could work is if they all fork chromium and base their browsers on this new fork, and even then it's not guaranteed to develop a real ecosystem of plugins since chrome has more users than all of those other chromium browsers combined.

So yeah you have to use Firefox if you want to avoid that, at least for now.