The "Left nav, new theming and responsiveness" has gone live.
Although the March 12th (2018) post about the motivations for this was well-received at a net +141 votes, the actual rollout wasn't, at a whopping net -198 votes last time I checked.
On English Language & Usage, the preview post garnered +10/-23 votes, compared to +26/-1 for the existing theme.
The new theme looks pretty unpopular, so my question is this: is the roll-out a fait accompli that the community can only tweak a little here and there, or is it possible for either individual communities or Stack Exchange as a whole to vote to not proceed with the planned changes?