When the Depression hits, German voters will break away from the more traditional parties to more radical factions.
Here are the OTL swings from May 1928 to July 1932
KPD ................................. 11% .... 15%
Social Democrats ....... 30% .... 22%
Zentrum ......................... 12% .... 12%
DDP, DVP, RDM ......... 18% .... ---
DNVP .............................. 14% ...... 7%
NSDAP .............................. 3% ... 37%
Others .............................. 12% ..... 7%
IMO, the NSDAP would split. The "left" (Strasserite) NSDAP would have 6-8%, the "right" NSDAP (Goering) would have 4-6%, another "right" NSDAP would have 4-6%, the KPD would have 20% (including 5% of OTL NSDAP), another 5% of NSDAP would go to very minor parties, and the remaining 7-13% of OTL NSDAP would be scattered among the DDP, DVP, RDM, and DNVP.
A left-center coalition of the SPD, Zentrum, other minor parties, and maybe the DDP could rule. So Weimar staggers on.
Unless... Röhm and Strasser are able to recruit a very large Sturmabteilung as OTL, and seize power in a street revolution?