Opera was the first "not IE or Netscape" browser I used. It would be poetic to go back to it now.
If you want to go back to the "original Opera", that is now Vivaldi.
Vivaldi already has a built-in adblocker in place, so Vivaldi ad-blocking doesn't depend on V2 being available.
This said, V2 shouldn't be removed at all because this will stifle the extension ecosystem. I predict that extensions will stagnate. Just because some ad-obsessed company killed V2 to stop an extension threatening their revenue.