What the Holy Roman Empire needed to survive

What if the Holy Roman Empire never collapsed and survived into the modern world?

It would need to preserve meaningful central authority and avoid the wars that reduced the emperor's power, producing a large and potentially formidable central-European bloc.

A surviving Holy Roman Empire is imagined as a substantial bloc in central Europe, but the answer first asks which version of the institution is meant. The participants contrast an earlier empire with stronger central authority and a later collection of more autonomous states. Continued survival is said to require enough central organization to hold the structure together. The Thirty Years' War and Seven Years' War are named as conflicts whose effects would have to change. The exchange offers those conditions without constructing a full alternative chronology.