Simply put, if the Allies stood up to Germany before Munich sold-out the Czechs, Germany probably would have had a massive mess on their hands if they had to militarily take Czechoslovakia… people assume a LOT of things, like the Germans were this massive modern mechanized monstrosity that few could stop… this simply was NOT the case in February 1938 when it first cropped up. Lets just assume, we look at a few things without the assumptions many put on Germany, and look at a lot of the realities if a war broke out before the Sudetenland was turned over to Germany, no Munich happened, and Czechoslovakia stood firm against Germany in 1938.
Czechoslovakia is NOT Poland… this seems obvious, but terrain alone is very much different… instead of flat plains, great for massive panzer formations and flanking units, you have a lot of mountains and rough ground… not exactly ideal for Blitzkrieg warfare…
The Sudetenland defenses were fairly well developed and would have posed a significant challenge… the Czechs had a fairly well-laid-out line of trenches, pillboxes and defenses all around the Sudetenland to defend approaches through rough terrain facing Germany… if these were manned and defended, it would be a tough approach for Germany to deal with under even ideal circumstances and with superior equipment.
The Germans did NOT have a quality advantage over the Czechs, especially in tanks. In 1938, Germany really only had two types of Panzers in service… the MG-only armed Pz-I… which was barely more than a training vehicle… and the laughable Pz-II… armed with a whopping 20mm cannon… once again… not exactly anything that is going to strike fear in your enemy. Pz-III’s were still in development… and mass production would not start till 1939… Pz-IVs just weren’t around… on the other hand, the Czech army was well armed with (at the time), a very capable Skoda CKD Lt vz.35 (later known as the Pz-35t, after the Germans got their hands on it)… the Czechs had nearly 300 of them at the time… these tanks were, in-fact, superior to anything the Germans had in 1938… quite a difference from the common misconception that the Germans always had better tanks than their opponents.
The Czech army alone, was well equipped and in a very defensible position, and could have held out far longer than Poland did, given the situations of 1, 2 and 3 listed above… in-fact, its entirely feasible, the Czechs alone may have completely halted an invasion of their country as long as the Allies didn’t give away their border defenses at Munich. This doesn’t even account for what would have or could have happened if more countries jumped-in to the defense of Czechoslovakia.
I’m in the firm belief, that had Germany militarily invaded Czechoslovakia in-whole before the surrender of territory at Munich, that it would have been a military disaster for Germany… and very possibly the end of the Third Reich, shortly thereafter.