hmm, that would complicate the Dutch revolt. I wonder if the Wettins would choose the side of the Spanish Catholics or of the Dutch protestants. If they chose the side of the Dutch protestants it would become a very interesting situation. Actualy if they don't too, would they bring in Saxony on the side of the Spanish?
Hm, Ive in the meanwhile also read Charles V gave all of Frisia (West Frisisa, Groningen, East Frisisa and even Dithmarschen in what is nowadays Schleswig-Holstein) as a seperate feudal fief, in exchange for a loan, and not as a stadholership. Bit confusing, that... but of course, with the stadholdership being hereditary that would be nearly as good as holding it as feudal fief, so that doesnt matter greatly.
Oh, and George was Albrechts son, not brother. Oops, misread that (they were talking about another Wettin there, Heinrich who also was Albrechts son and hence Georges [younger] brother. Heinrich inherited Albert's hereditary position first, until he gave up). Anyways, Albrecht was the founder of the Albertine Saxon line, the line which ruled from Dresden and originally was the minor line, until the Schmalkaldic War. George was one of the most vehemmently anti-Reformation princes of the period, but IOTL, his two sons predeceased him without children of their own, and hence the Duchy passed to his brother, said Heinrich - who introduced the reformation in the Albertine lands.
Which, come to think of it, would be the perfect pretext for Charles V. to not let him inherit the hereditary stadholdership or fief or whatever the hell it was... so if we want a Wettin Frisia, George's son Johann needs to at least live long enough to produce a son of his own. And that would probably mean a Catholic Saxony and Frisisa allied to Charles V., yes. But keep in mind that the Electorate of Saxony at that time, the co-leader of the Schmalkaldic League was Ernestine Saxony, not Albertien Saxony - the Albertine Duke Maurice IOTL betrayed the Protestants to Charles V. anyways, so not that much changes - except the very

prospect of a Saxony-Frisia personal union
Do you have any idea why most of (protestant) Germany was Lutheran and most of the Netherlands Calvinistic? Maybe it has something to do with Habsburg ruke? Actualy it wouldn't even surprise me that East-Frisia became Calvinistic because of the Dutch influence.
Well, Calvinism also was the main protestant movement in France and Hungary, too, and "only" in Germany and the Scandinavian countries Lutherism was predominant. The roough explanation for that is quite simple: Luther's texts were hardly ever translated from German, whereas Calvin wrote in French. Hence, you got a division roughly along lingual lines - after all, in the Scandinavia of that time, German was widely used, too. Of course, that means Lutherism could also have gotten hold in the Netherlands, but, eh... its a rough explanation as said

(Switzerland is explained by Calvin's and Zwingli's geographcial position there)
About the Calvinistic Nassau, I always learned that William of Orange was at first raised as a Lutheran, but when he became (heir of the) prince of Orange he was from that point raised as a catholic (while his family remained Lutheran). Eventhough he was officialy catholic he had a lot of sympathies for the protestant cause and when the Dutch revolt started (and he became the leader of that revolt) he became protestant again. He only chose Calvinism because most of the Netherlands was Calvinistic. I presume that that is the only reason the house Nassau became Calvinistic.
That explains Nassau-Orange, but not the other Nassau lines

Some Nassau lines reoncverted to Catholicism, but the protestant ones all were Calvinist, while their land was Protestant. Hohenzollern, btw, had a similar reason: They took over calvinist Cleves in West Germany. At least, thats the explanation Iev heard. Still, it meant they ruled as Calvinists over an overhwlmingly Lutheran population. Whereas Maurice of Hesse-Kassel converted for purley religious reason, sparking the en dof Marburg as an all-hessian university

mad

and an inheriitance conflict with Hesse-Darmstadt over the Marburg lands that lasted over centuries. But, that, too, is an example of Calvinist rulers over an overwhelkmingly Lutheran population, so, yes, that happened often, apparently...
BTW Do you know when people stopped speaking Frisian in East-Frisia and started speaking lower Saxon? It would be cool to have an independant Netherlands with 2 provinces speaking Frisian, but I am afraid the POD is already too late.
I have the same vague feeling, but I have no exact idea, either. The Freesian Freedom ended in this period - to be exact eactly then when Albrecht was granted those lands. Wiki says the 15th century is also where the declien of teh Frisian language began, but I have no idea wether this coincedes with the political decline. Maybe, if the Frisian lands were united udner a halfways strong ruler... sure, the Frisisan Freedom wouldvbe ended, but maybe the Frisian language couldve survived even outside of the Prov. of Frisisa...