This is already happening, but I don't know to what extent (especially over multiple countries), but we moved into our extremely well insulated house (thing 3 layers of glass) in the Netherlands mid 2020. Heating happens using a ground source + heat pump, cooling using just the ground source and passive pumping, ventilation is centralised and uses heat exchange.
During some 30/35+ waves of the last few summers we kept it below 23 degrees Celsius inside, even over many days of heat.
How do you handle light? I'm in Hilversum and the houses are just ovens.
Until recently I lived in Ireland and people looked at me like I had 3 heads when I talked about air tightness, deciduous trees in front of south facing windows, and eaves/awnings - the idea that you might not _want_ as much light as possible baffled the dinosaurs in planning.
I hope the Netherlands is better but I still see an awful lot of windows with no protection from sunlight. Eaves are perfect (and deciduous trees) because you can angle them such that you get light in the winter but shade in the mid-day summer sun.
