The construction of (fairly) new nuclear power plants near the shared borders with Belgium and France is actually an argument I hear quite often.
In many debates people argue about why Germany should go ahead and quit using nuclear if the neighboring countries keep building and running new plants, also posing a huge risk to Germany in the event of a catastrophic failure (actually the risk in case of a failure is probably higher for Germany than it is for France or Belgium).
I don't think Belgium is going to build new nuclear plants any time soon. The retirement schedule is pretty tight and we may choose to keep 2 reactors running for 5 or 10 years (unlikely) but the operator (Engie) is sun setting them whatever happens and has set no money for upgrading them.
They already wrote the loss of revenues in their accounting books.
In many debates people argue about why Germany should go ahead and quit using nuclear if the neighboring countries keep building and running new plants, also posing a huge risk to Germany in the event of a catastrophic failure (actually the risk in case of a failure is probably higher for Germany than it is for France or Belgium).