That, and/or a sandbox model where plugins cannot escape a sandbox. And/Or a setup where a plugin's runtime is isolated from main WP and other plugins and it c

That, and/or a sandbox model where plugins cannot escape a sandbox. And/Or a setup where a plugin's runtime is isolated from main WP and other plugins and it can only communicate with WP over a tiny and very much hardened API. so many possibilities. This problem has been solved mostly. Just not for PHP (that I know) and certainly not for WP.