I think the biggest ask the article is making in an unreasonable way is to somehow find millions of contractors who can actually go home by home and refit the heating systems in a timescale that'd actually be relevant for the war in ukraine.
If Germany wanted to switch everyone over to a different kind of lightbulb they'd need to ensure the production capacity to make the new bulb exists and set up logistics to actually distribute it. You'd have a fair amount of non-compliance due to paranoia and other factors but I think you could probably get it done with a year or two of warning... Once you hand the household the lightbulbs they just go through and replace them all and dispose of the old bulbs...
To change out a heating system you need to remove large appliances, install other large appliances, fiddle around with gas lines and the breaker panel (probably you'd need to replace a fair number of breaker panels in older houses to handle the higher throughput), deal with the wiring which might be unsafe for the power you'll be sending over them... then you'd need to actually install the radiators, that involves tearing up floors to do it right (floor radiation can be extremely efficient and generally creates a higher apparent heat than traditional radiators placed next to windows for fire hazard reasons), or else popping in some other more module style of radiator. Those radiators might use direct electric generation or you might opt for additional boiler capacity (much more sane for efficient stand-radiators) which comes with piping requirements along with a lot more wiring work.
All of that is in addition to all the problems I mentioned around lightbulbs - you're still going to need to actually produce and distribute all the material needed to execute this change.
If you, as a person, want to swap out the heating in your house it'll be a weeks (maybe if you're lucky) or months long renovation - imagine trying to do that on the scale of a country, the only way it'd be even plausible is if you essentially drafted large portions of the population and trained them up on trades - that might not be a terrible economic investment, but it certainly isn't going to happen fast.