I don't think it's likely that core will actively break these things. If they removed the ability to filter HTTP requests, they'd break a lot of plugins and likely a lot of sites, which would become a nightmare, because their main selling point is "one click install, never worry about it again" -- they primarily compete with Wix, Jimdo etc, not with other CMS.

If they changed their backend to disallow this implementation from accessing it, they'd also break it for older versions of WP (which feels like the majority) and cut off the upgrade-path for those sites.

WP's heavy use of filters & actions are what makes it bearable to work with for developers, and without the plugin ecosystem, Wordpress would be no serious competitor to anything.

I don't know if this will work out, the code looks worrying - they support all the way down to php 7.2, but OOP and composer don't require php8. On the other hand, so do most WP plugins, and core does too.