I seem to remember quite a few examples posted to HN over the past few years of companies "declaring RTO" and then finding that rank-and-file employees largely just ignored it, and the companies never did anything about it because they can't fire everyone.

"I declare RTO" can only work if you have critical enough mass of employees who believe the bluff and actually come into the office. This is definitely an area where a workforce that is organized and works together could hold out forever, but the tech worker mantra is "unions bad" so collective action is difficult.