Given the facts, world economy crise, "negative" (democratic parties in absolute minority) majority in the Reichstag and Hindenburg as president, which would be also doubtful if Hitler died or disappeared in 1924, most probably then Marx, Zentrum, it is more propable the Republic would have recovered form the crise as there was an upgoing of economy since the 2nd half of 1932. So in the elections after it the democratic parties would have gained majority at last in 1934/35. Then there would have been no Hitler and de facto also no Versailles. The Republic would have been reformed- perhaps, as the introduction of a real constitutional court and the ban of non- democratic, perhaps without parlamentarian monarchists, parties would have lead to a consolidation of power for the democracy.
A communistical coup or similar take over I can´t see. But then Stalin would have been the agressor. In the 1940s. I would assume about 1945. Then he would have challenged the western world but given the capability of the united forces of Germany and the Western allies, perhaps excluding the USA, Stalin would have had no chance. But this is massive speculation.
Adler