This has been obvious to everyone who knows that the key feature to the devs of these browsers is “-based.” None of the chromium-based browsers are anything other than UI tweaks and certain extensions being included by default. None of them rewrite significant parts of the browser engine, because that would be too much extra work.

The only projects which have a hope of maintaining MV2 compatibility are those who are a hard fork of an earlier version of chromium or a totally different engine.

To my point: The article mentions that Opera still says they will maintain MV2 for as long as it is “technically reasonable.” Mark my works, Google will find a way to break Opera’s MV2 patches that makes it too hard to maintain.