Without the Ruhrgebiet Prussia will have a much smaller industry - it still has upper Silesia of course but that is nowhere as significant as the Ruhr. With more landlords and more Poles it will also be even more conservative than IOTL.
It would be important to know what happend with the Rhineland, is it a single state or does it become split? The first is more likely since the Powers wanted to prevent France from expanding again.
What will be very interesting is the German Unification. IOTL it was impossible to unite Germany without Prussia. ITTL the Paulskirche Parlament might decide to form a third Germany aside from both Prussia and Austria.