No, the Hohenzollern were always the first and only real choice. (Of course there also was a push to reinstate the monarchies of the member states, like Bavaria, Saxony and so on, but neither of those was supposed to be a nationwide monarch). That being said, German monarchists faced the problem that many of them considered both Wilhelm II. and his son, the Crown Prince, to be wholly inadequate candidates and the sons of the Crown prince were viewed as being too young. That's why Hindenburg always, until his death, maintained that the monarchy should be reinstated at some point in the future without saying when. He was unwilling to help restore Wilhelm II. to the throne and unwilling to breach the line of succession. For that reason, the idea of a regency was thrown around. Hindenburg was of course a candidate to be that regent and in 1931/32 Heinrich Brüning toyed with the idea of asking one of the Dukes of Mecklenburg (I think the same guy that was supposed to rule the United Baltic Duchy in 1918) to become regent.