Monarchism was fairly significant in OTL and by becoming President, Hindenburg hoped to serve as the vessel for the Kaiser's ultimate return. Indeed, Hitler made vague promises to ultimately restore the Kaiser (he made promises about everything to everyone, but this tells us something about what the Junkers thought they were getting when they supported him).
But actually bringing the Kaiser back seems nigh on impossible. He had no widespread credibility and the popular resistance would be massive. And there's no obvious reason to do it - the problems in the later Weimar era were (at least as far as everyone could see) with the legislature undermining the head of government, not with the head of state. Simply exchanging the Presidency for a constitutional-limited monarch doesn't solve those problems; and even if enough people are minded to do away with proportional democracy, a stronger (American-style) Presidency is a more obvious solution than bringing back the Kaiser with all his old powers.