What if the Nazis hadn't invaded Czechoslovakia in March, 1939?

The Nazi invasion of Czechoslovakia in March, 1939 -- explicitly forbidden by the Munich agreement of 1938 with Britain and France -- was really the last straw in determining that Hitler was simply too dangerous to be negotiated with seriously, or trusted at all, about anything. While the remains of Czechoslovakia were certainly no threat to Hitler, its resources and arms were potentially very useful to Germany's arms program and economic development. To some extent, Neville Chamberlain had seen the Munich agreement of 1938 as a test for Hitler, to see if it was at all possible to do business with him, or he would simply act like a pirate and a thief every chance that he got. He failed the test, and from that point, Britain saw Hitler as an enemy who had to be destroyed. So what would have happened if Hitler had simply refrained from invading Czechoslovakia? The fact is, the Munich agreement had left Czechoslovakia so unstable that it's quite possible that it would have collapsed into Civil War sometime into 1939 anyway, and that German intervention would have been required and requested by the international community, as a whole. Under such circumstances, the Munich agreement wouldn't have been violated, and Britain and France would have seen Germany as a responsible member of the international community. Or, even if the Czechs managed to survive, they would have been compelled to remain a close ally of Germany. In either case, it might have been possible for Hitler to pursue his Lebensraum agenda to the East. After all, the British had no more love for Stalin than they had for Hitler. If Hitler proves more amenable, why not support Hitler, in his plans for the conquest of Soviet Russia, what's the risk for Britain? Likely, this would have effectively moderated or eliminated Hitler's antisemitic agenda, since Hitler would have been being supported by the great Western bankers and capitalists in his desired crusade against Communism, the Red Menace. Now, the problem remains, how exactly can Hitler conquer the Soviet Union? Hitler appears to have been emulating the Mongolian Golden Horde in the thirteenth century, or perhaps Tamerlane the Great in the fourteenth century. The problem is, the Russian population had increased some twenty fold since that time, so their conquest was a correspondingly more difficult proposition. Even with the limited backing of the British Empire, and even alliances with Czechoslovakia and Poland, perhaps, it's not clear that Germany has much of chance to really conquer and colonize Stalin's vast empire. To some extent, his OTL approach of simply stealing whatever he could get to build arms as quickly as possible, to steal as much more as he could get, might have been the optimal, if ultimately unsuccessful, method. Or, is there some combination of alliances Hitler can develop, if he behaves himself, that will allow him to conquer all, or some of the Soviet Union?