This saying is attributed to Matthias Corvinus with regards to the Habsburg marriages that brought that family Spain and in the preceding generation, Burgundy and an attempt at Brittany.
But say Marie of Burgundy has a brother, or her younger son survives and Burgundy is carved off the Habsburg bloc, while Juan of Aragon, prince of the Asturias leaves surviving issue. In other words, no Hasburg-Spain, and perhaps no Habsburg-Burgundy or at least if it is, it's under a cadet branch. How might Spain and Burgundy develop with no Habsburg rule? The same? Differently?