For a while now the transition away from Manifest V2 (MV2) to MV3 has been on-going and it looks like it is entering its final phase of deprecation, at least, in the case of Google Chrome. A recent discussion thread in the w3c WebExtensions Community Group GitHub repo has highlighted how the latest and upcoming versions of the most popular browser are expected to be its final releases with support for MV2 extensions.
What this essentially means is that the tricks and bypasses that were used to keep MV2 extensions like uBlock Origin and others alive will not work any more on Chrome, or at least not for very long. For example the Windows Registry mod that could extend MV2 availability will cease to function after Chromium version 151.
It’s not an ecosystem of one, though one is very dominant.
You can compare it to Linux. It’s not the only Unix-like kernel, but it’s similarly dominant. If you want to create a new distribution, it doesn’t make any sense to spend a decade trying to write your own kernel rather than just using the Linux kernel (insert GNU Hurd jokes here).
Is that an unhealthy ecosystem then? I don’t think it is.
What makes the chromium situation unhealthy is Google’s ownership and control, not that it’s the preferred engine for other browsers. I mean, even a company as large as Microsoft gave up trying to create their own engine.