Blink supports Windows, Android and Linux better than WebKit or Gecko does, to name at least one one reason. If it weren't for uBlock I'd probably be using a Chrome fork right now.
Google has already shown that they will slowly and methodically use every lever at their disposal to nerf ad blocking, regardless of what the user base thinks.
It's the exact same playbook Microsoft is using to block users from logging onto their own computer without using an online Microsoft account.
Given that Google has already started working to limit sideloading on Android, those days seem limited.
Blink is an open source project. If Google updates Chrome and Android to refuse sideloading at all, you can still fork both projects.
Your entire argument relies on a hypothetical you can't prove and doesn't scare anyone. To Android users you sound more like Chicken Little than the Boy who Cried Wolf.
Wipr and UserScripts on Safari prove to me that that's not a real issue...I understand compatibility problems are still issues, but ads/etc. are a fully solved one for Safari users.