As others have intimated, there's a very big difference between the survival of the pre-Reichsdeputationshauptschluss Holy Roman Empire, and the survival of the abortive Holy Roman Empire created by those reforms.
I think the survival of a post-reform Empire is going to end up not very different from the OTL German Confederation - the territorial consolidation of the middle states and the disappearance of most of the smaller intermediary bodies (the free cities and ecclesiastical states, in particular) has already happened at that point, and the further progress of that to include the Imperial Knights and some of the lesser comital states is perhaps inevitable.
On the other hand, if you prevent the reform from happening, you get a very different world, with all the prince-bishoprics and imperial abbeys and free cities and imperial knights still in business.