From a historical perspective, the Swedish civilization and the House of Vasa are closely related. So just as part of the European Royal House was added to Germany and France, the House of Vasa should definitely be added to Sweden. Sweden definitely needs House of Vasa, especially in treaty games. In this way, Sweden can meet the need for 1 population of rifle infantry more easily. At the same time, the addition of House of Vasa to the Swedish civilization would be more appropriate in terms of the historical realism of the game.
In my opinion, the Royal Houses need some remodeling in the future. I will just talk about it on the example of Vasa Royal House.
At the moment, some of the units located in the Royal Houses seem to be held there until a full-fledged civ is released. The best and most obvious example is the Winged Hussar, which is the most famous Polish unit and is located in the Vasa Royal House. I hope this and other Royal Houses units in the same situation as the Winged Hussar will be added to full-fledged civs in the future, and will be replaced by brand new units.
For Vasa Royal House, I think Finno-Ugric units as a replacement for Winged Hussar would be a nice option.
House of Vasa should definitely be added to Sweden civilization. I hope House of Vasa will be added to Swedish civilization instead of Polish–Lithuanian Commonwealth civilization.