I can see that being an issue if the web is centralising around one proprietary engine, but why does that apply to Blink? If Google turns completely evil that won't take away from all the webcompat, optimisations, and security in Blink, and any bad feature (ManifestV3) can be patched out easily. Mozilla could switch to Blink (and I think they should, and Apple too, they clearly don't have the manpower to maintain a whole engine and keep it modern and secure, see my other comment in this thread; there are many more 0days with Safari and Firefox than Chrome) and it wouldn't harm the web in any way, because they can just swap out bad components with their own, and still reduce their dev time requirements by orders of magnitude compared to today. You have Intel, Samsung, tons of companies contributing to Blink, to a much, much greater extent than Gecko or WebKit.

If every browser switched to Blink, that would actually benefit consumers, because right now Chrome basically has the enterprise market on lock, since nobody cares to test internal webpages on other browsers, and Chrome has better enterprise features (though I don't know how much of that is to do with the engine); and many consumers also just switch to Chrome as the first thing they do, because they've run into compatibility issues with Firefox or Safari and they just want to access the web without issues. If every browser used Blink, you'd have a lot more people using Safari and Firefox, just because most people don't want to keep two browsers around (Firefox + Chrome or Safari + Chrome) when websites break (which is not often, but often enough, trust me). I really hope we see this.