By now, even the power plant operators aren't very interested in keeping them running for longer because they already planned to turn them off and dismantle them. Keeping them on for longer means a significant investment to them, for unknown benefit as the societal rift will inevitably break open again. They might invest (so they can continue to operate things safely), delay the dismantling (probably also costs money because they likely started hiring companies already), only to be told a year later to shut things down again (all that money for nothing).
An issue in that has been that renewables build-up has been all but sabotaged politically in the last years, and that storage technology didn't develop as well as estimated, making gas necessary as a peak load compensation mechanism, "hopefully" temporarily. Gas turbine operators are whining for years that they're operating at a loss but they're forced to continue to operate (getting the loss just about compensated I think) to ensure the grid's safety.
Other than _that_, gas is mostly used for heating which is a distinct system. As such, any consideration of "nuclear vs. gas dependency in Germany" is something that seems to be mostly discussed outside Germany: No matter how many nuclear power plants we keep up, gas boilers just don't run on electricity (except for their controller module).
As for booking a contractor 20 years ago: There are funding programmes to encourage folks to go for heat pump systems and other modernizations. The last electricity heating system that was widely deployed in Germany _was_ horribly inefficient, which is no surprise with technology that was already old in the 70s, and the idea "electricity for heating is a waste" has stuck. The political sabotage that I mentioned extended to not really caring about correcting such misconceptions.
you’re still looking at about 4 trillion kWh of energy/yr (possibly a month - hard to get good data) that would be needed to do that switch.
most of it during winter.
Germany currently produces a little over 500 billion kWh of electrical energy a year.
So to replace natural gas for heating in this scenario, Germany would need to produce 9x the electrical power it currently produces. Most of it during the winter.
And not having enough production would kill people.
It isn’t a matter of not having enough heat pumps or people to install them, that’s just the immediate road block if you individually wanted to switch.
It’s a fundamental economic issue that would require investment on a scale heretofore not considered outside of world wars. And maybe not even then.
Right now, we don’t even know of a storage technology that could even work at that scale, let alone what it would cost to do it.
And depending on which way climate changes go, the size of storage needs to be potentially arbitrarily large. The more uncertainty you have, the larger it needs to be.
Unlike a fossil fuel, we don’t have (essentially) arbitrarily large reserves we can pull from, it all has to be made and stored in advance by the same infrastructure that produces your normal production.
The "gas boiler in every second home" scheme locks us into gas to a degree that even "a natural gas burning turbine in every city" wouldn't. But locked in we are.
The push for renewables or the rejection of nuclear power plants is orthogonal to why Germany is stuck with Russian gas.
As mentioned by another comment: even if we were to send all that gas used for heating into gas turbines instead and use the generated electricity to operate the heat pumps, we'd use less gas (because it's using environmental heat energy in addition to the intrinsic energy of the gas).
That brings the bonus that we could look into alternative power sources (of whatever kind: I'm sure France would be more than happy to assist bringing up nuclear reactors again, although that's unlikely to happen in Germany for a whole bunch of reasons) when gas is difficult to obtain because electricity is electricity.
But apparently we don't have a sufficient number of people who could do the installation, plus it'd be expensive, and even discounting that, I'm not sure if "We need 12 million heat pump systems. Next quarter?" is something that could _possibly_ work even under normal circumstances (nevermind the supply chain issues we're currently dealing with globally).
That's why I brought up the 150k installed units per year: There's probably room for improvement (I've been thinking that there must be a very profitable career in heating installations), but even if we can install 600k a year, we're still looking at 20 years before we get all the old cruft converted.