I am optimistic about the potential to shove consumption around within the day-night cycle - particularly if the shift is consistent.

So am I. Chargeable hybrid cars can do most of that.

About the longer term (synoptic) variations, what's left of those after the European supergrid, can be taken care of by gas turbines, but burning electrolytically produced hydrogen from excess wind. Yes, an inefficient solution, but if we're talking about 10% of production we can live with that.

I see you didn't mention the annual cycle: it's a biggie, and nuclear isn't very good at following it. Wind -- or rather, a suitable mix of wind and solar -- is much better. And I'll say again what I said before: most of our energy use that produces CO2, like 3/4, does not involve electricity. Like space heating, where there is a huge savings potential through better building, heat pumps etc. Also, process industry and metallurgy. Bringing down these uses will involve electrification, which will raise electricity consumption, something I do not see in most plans. Something to be aware of.

('Real time' feels like it would lead to Enron-style scenarios, so perhaps monthly or so updates would be better.)

And this

The much under-rated resistance heater has many attributes that make it ideal for this purpose.

They can be turned on and off quickly.
They're very cheap. So when they're used for hundreds of hours a year, rather than thousands, their cost per kWh is much much lower than heat pumps.
They're very reliable, and need minimal servicing.

So, a heat pump would be terribly wasteful in this situation, of being a backup to the main boiler, to be used in emergencies or at times of very very low electricity costs; and a resistance heater is perfect.