Let's say that the empire unifies in the 1500s, after a more successful Reichsreform. Instead of a collection of small states nominally part of the same empire, they are bound together in a more centralized structure.
So, my question: what would this empire look like? Would the various competing dynasties have to be stripped of their land for this centralization to succeed? Or is there some way that the federal structure could be implemented while the minor houses retain their land?
How would this unified empire effect the world?
(also, let's assume the Reformation never happens, so all of the HRE if Catholic.)