I once wrote that if the New Deal had failed politically, the most likely alternative for America would not be revolution or civil war, fascism or communism, or even Huey Long or Upton Sinclair. It would probably be Arthur Vandenberg or Alf Landon. I joked that this was the most boring fact in alternate history...
(The point is not that America is unique, and that therefore it "can't happen here." Rather, the point is that *most* well-established democracies--democracy in Germany and Italy and Spain was hardly "well-established"--did in fact muddle through in the 1930's, often under center-right governments like the UK under the National Government, Australia under Lyons, etc. Even France was governed by centrist or conservative governments for most of the 1930's, the Popular Front being a relatively brief interlude.)
And how well-established was the Taisho democracy, by your reckoning? Seeing how they didn't muddle through either.