IMO he should have been writing about cybernetics instead of looking nostalgically at militant struggles from the past and trying to project them into the present. "Power" found something better than confrontation, discipline, normalization, etc. It has instead coopted opposition and started feeding on it.
It's not a coincidence that there was a lot of leftist terrorism at his time. After failed may 68 all these militants were desperate as fuck because time for another uprising was running out when consumerism and mass media was turning people into passive masses. (Bombings by RAF were explicitly an attempt to wake people up from this, they also targeted shops for that reason.) That's not really power in Foucault's sense anymore, it's a system that integrates and manages.
And may 68 itself has inadvertently led to that. The response to it was to let people do whatever, no need for "discipline and punishment" anymore, we can sell them Marx shirts instead, feed on their little resistance to make the system run better. It's not just traditional liberalism, but a further development of that liberalism into a total integrated system. In his time even society started to be run literally by computer systems and feedback loops that incorporate everything into its calculations.