Have the Ernst Röhm fraction of the nazi party win over the Hitler fraction and suddenly a civil war is likely between Ernst Röhm and his SA on one side against conservatives on the other, incl. the Reichswehr, church and monarchists.
Germany's last Crown Prince - Friederich Wilhelm - apparently had political ambitions after the abdication, hoping for Hitler to restore the Hohenzollers - something like in Italy where Mussolini's fascist regime was inside the formal frame of a Monarchy. If Hitler leaves the scene in say 33 or 34, and Röhm enters, I could see the conservatives looking for a gathering point against the nationalSOCIALIST Röhm, and that the Crown Prince could be that.
In Entente propaganda from WWI he was called the "Clown Prince" but AFAIK he wasn't that hopeless and quite popular anyway.
Regards
Steffen Redbeard