I don't know, I doubt the League of Nations would have taken any stronger action without Germany since the decisions that made it near powerless were made before Germany became a problem. I also doubt the UK would go against the LoN's decision since Chamberlin was commited to support them and avoid wars.
Without Hitler I think that the Wiemer republic would have survived and rearmed moderetly since Uboat production and Tank research had resumed before the Nazi's gained power. I doubt Germany would have turned communist, the reds attempted an uprising in Berlin after the war (Which is why the Government moved to Wiemer), but it didn't get much support and the army stamped on it. Germany may well have got some of it's lost land back peacefully since many in Britain and France were saying Versailles had been too harsh on Germany in the 20's and 30's.
Possibly the USSR would make a move on Poland resulting in an Europe vs USSR war sometime in the 40's.