Last time I checked we had a massive overconsumption of basicly all resources in the EU, so a slower economy is hardly a massive problem. Even more so since labour shortages strengthen the workers against the company owners. So the rich get less, while the poor at least have a stable income. The best thing we can do, is to lower expensive imports of fossil fuels. Especially from dictatorships.

Also this is not just a European problem. All continents besides Africa have a fertility rate below replacement today. Europe is able to attract migrants, due to the still high quality of life, so we have much less of a problem, then say China.