Unless, of course, the economic majority accepts the new rules. In which case the stubborn few stragglers find themselves on a fork unsupported by the security of massive hashpower.
That's not how a HF supported by consensus works.
I'm talking about a scenario in which the miners suddenly decide to 'change the rules' which would be the case with this ridiculous plan that was proposed. There's no way that businesses that are running on less-than-optimally maintained versions and some unusual ones (e.g. Bitcoin ruby) could upgrade very quickly (testing and deploying takes time IMO). Besides, once you give in to such coercion the chances that someone will attempt to do this with even less preferable "changes" become higher. If the HF was 'driven by' consensus, then the economic majority would most likely accept the new rules.
The "ridiculous plan" (or some derivative thereof) is
supported by ~the entire Bitcoin economy (note that the Chinese exchanges also support larger blocks based on the stances of the Chinese pools that are owned by the same entities).
It is only the blockstream core devs, who work for a company who can only possibly turn a profit if transaction fees skyrocket, as well as the one person who can effectively control the public conversation about the block size, preventing many "normal" people from being well informed (although this really does not matter because most normal people's opinions are not going to matter in terms if the economy accepts a fork or not).