In principle this is possible, if and when all other circumstances remain unchanged, but this is very unlikely. First, there must be strong safeguards - such as strict fiscal rules, mutualized guarantees - which will mitigate upward pressure on interest rates for better-rated states.

But what is more important in my humble opinion are the new geopolitical and economic realities we are facing - like climate change, an aging population, immigration, the war in Ukraine, China’s coercive policies, etc. All these issues can and must be tackled together rather than in isolated/national measures. A joint defense bond, for example, would also solve the free-riding problem.

The urgency of further sharing public goods across EU countries will undoubtedly increase, and so it increasingly makes sense to share the burden. Some EU measures in recent years - such as the European Stability Mechanism (ESM) - are first steps to address these issues, although they do not (yet) offer the possibility of full debt mutualization. But we in Europe must take the next steps in this direction.