They are unlikely to proceed with their scheduled nuke shutdown for 2022 given Russia's actions. Perhaps they will consider reopening the nukes they've shut down recently as well.
Germany needs to replace gas heatings with heat pumps and gas usage in industry with hydrogen to reduce the dependency on Russian gas.
The problem is not a lack of electric energy (this year also 12 coal plants will be shut down, while a lot of renewable energy is being installed). Reopening the nuclear plants will not help.
Longer term, you are right about the need for more heat pumps to replace gas heating, and I'd also add extra insulation to that to reduce the heating needed from any source. The heat pumps can be powered by nuclear, renewables or gas depending on cost and preference.
Anyway, renewables alone can't completely replace coal or gas, since their output is relatively unstable and unpredictable. So far Germany has been ignoring that problem while shitting on neighboring countries which cover for their fluctuations and which obviously can't pull the same trick now.
Europe has an integrated grid. The purpose of this grid is to balance fluctuations. NordLink (https://www.tennet.eu/our-grid/international-connections/nor... ) was explicitly build to access the more than 100 TWh of available pumped water storage in Norway to store wind energy. And I guess Norway is making some money from it. Denmark has an even higher share of wind energy than Germany (70% last week). The Netherlands got 30% of its energy from wind last week, Austria 26%, Poland 25%. France uses German electricity when it is cold in winter and resistance heating is using more energy than they can produce or if they have to shut down some nuclear plants because of security issues (https://www.express.co.uk/news/science/1549986/macron-france... ). They are all pulling the same trick.
Again: Balancing is the purpose of the grid and not "shitting on neighboring countries".
I suppose given recent developments this whole discussion is moot though :)