As Condo suggested, he might decide it'd be best for the German Branch of the family to reign a territory that is inhabited by Germanic peoples.Simple, is this plausible and how could it happen?
I once read somewhere that Ferdinand of Aragon wanted to divide is grandsons inheritance, Charles getting the Burgundian and the Austrian possessions and Ferdinand would get the Castille and Aragon possessions,
This plan is a more plausible oportunity to have the Netherlands and Austria under the same Habsburg branch because Charles would never give up the Netherlands
Wel Ferdinand was raised in his grandfather Ferdinand's noble court in Spain, as opposed to Charles who was born in Ghent. I always thought it made more sense for Ferdinand to get Spain and Philip to get Austria, Burgundy, and the HRE.
Charles was the senior son, hence he gets the senior inheritance - or as originally planned, all of it, anyways.
Seeing that the HR Emperor title was not hereditary it did not come automatically with those territories. De facto it did, yes, but Charles himself tried (and failed when Ferdinand became his sucessor as Emperor) to unite the titles of Spanish King and HR Emperor.But the senior inheritance, at least in 1517, was the Austria-Burgundy branch, it was the paternal line of the family, it included the Imperial title, and the Netherlands one of the richest the countries in Europe.
No, Burgundy(the Burgundian Netherlands) was the wealthiest country in Europe prior to the beginning of the flow of American Gold and Silver into the Spanish Coffers.Sure, Austria and Burgundy were the corelands, but Spain were the more profitable and powerful lands, even before colonsiation of the Americas.
I think this (the latter idea, not the one in the title) requires Charles not becoming "fascinated" with Spain as much as IOTL (he chose it as retirement, after all) and as a consequence he would have educated his son in the Netherlands instead of Castile.
The Cambridge Modern History said:But, when in 1547 Charles consented to a marriage between his elder daughter, Maria, and her cousin Maximilian-it was actually celebrated in the following year-the hoped-for dowry of Milan or (what would have suited him better still) the Low Countries, was withheld.