The Austro-Hungarian empire was considered to be a successor state and claimed the title for a time, and basically the German Empire and Austro-Hungarian empire were somewhat viewed as successors along protestant and catholic lines - unifying the division of the two under a 'new' ideology was a big part of third reich ideology (irrespective of how bad naziism was, this is a huge part of the history of the broader topic of 'german unification') .
This article mentions neither historical austria-hungary, the reformation, the anschluss, or modern day austria, so it seems more than a bit lacking from my perspective. But again, not a German nor a Historian so I could be missing something..
Well, that was one of the ideas behind the "Third Reich" (Roman Empire, HRE, then German Reich). Of course, it was under Hitler, not any hereditary emperor.
> If I remember the last HRE was still around for many years after the outster of Napoleon.
No, the last recognized HRE (Francis II) was defeated by Napolean.
But technically, there still is an heir, although his family has renounced any claim to that or any other title (among other reasons, because Hungary and Austria don't permit the use of such titles): https://en.wikipedia.org/wiki/Karl_von_Habsburg
Hereditary (and especially primogeniture) wasn’t as big a deal under any of the Roman Empires as it was for European monarchies. Even when an emperor had heirs, they were often adopted.
https://en.wikipedia.org/wiki/Dissolution_of_the_Holy_Roman_...