After a recent re-watch of the Mandalorian series with the new context of S2 and S3 Rumors, I realized something new.

Grogu, as part of the Yoda species, ages very slowly. Unless they do something with Time Travel (which I doubt), by the time Din Djarin is dead of old age Grogu will still be the equivalent of 11-12-ish (divide Yoda species age by 10 to get human age equivalent). Even if this aging process is inaccurate, there probably won't be much time when Mando and Grogu could fight together in any kind of intense fight.

I also know that Star Wars (especially Dave Filoni/George) like to put inter-generational legacies in (Vader-Luke, etc.). If the above case with Grogu is true, then such a situation would be less likely. The solution would be as Cara Dune hinted: by returning to Sorgon and marrying the one widow (I forgot her name), he could then train his stepdaughter as a normal human Mandalorian and still be well within the time constraints of inter-generational "co-op" battles, something seen in Rebels between Sabine and her Mother.