A Wendish state in I guess Pommerania, Pommeralia, Mecklenburg and Brandenburg could very well end up in a Bohemia-like relationship with the Empire. They might become a second Imperial Fief with a hereditary Royal Crown. However it won't prevent Germans, Dutch, Flemish, Poles and Danes from moving, in part invited by the local rulers, which at the time was a common way to develop regions. I do agree, that for a ruler to accomplish that, would be quite a feat, since local opposition will grow, and they will get aid from the Empire, Poland and Denmark.
Also the local ruling houses of Mecklenburg and Pommerania even stayed in power after said take over, so it not as clear cut, in fact the house of Mecklenburg (Niklotiden) still exists today. Sure they adopted much from the dominant culture in the Empire (which was not exclusively German, as far as German as we know it was a thing), but they like Poland, Hungary etc. adopted elements from the broader Catholic Western European culture (which at it's core had the former Carolingian Empire and England).