It is true that we would require a different Hitler (but this is wholly doable with the right PoD) and that the missed early annexation of Czechia would give Nazi Germany some serious short-term economic hardship. Nothing, however, that cannot be settled by slowing the pace of rearmament for a year or so, to let the economy redress itself. However, in the medium and long term, the political and diplomatic benefits would be huge, and a game winner for Nazi Germany.
Respecting the Munich Agreement means that Germany remains a trustworthy partner in the eyes of Britain and France. We have to assume, as it is natural, that the same change that makes Hitler see the wisdom of leaving rump Czechoslovakia alone also makes him rein his territorial appetites about Poland to what would be acceptable to Britain and France (recovery of the Corridor and Upper Silesia), and he moderates German dipòlomatic stance in the Danzig crisis accordingly.
If he does, it is all but sure that Britain and France would maintain the appeasement strategy about German irredentist claims in Poland: Warsaw and forced to accept the 1807 border at the Munich II Conference, and it resists such a deal, Poland would be left alone to fight Germany, in a limited German-Polish war that would result into the 1914 borders for Germany and fascist satellitization for Poland (the reasonable maximum that Britain and France could accept without question).
After that, there would be no further major issue for contention and antagonism between Germany and Britain/France, and some kind of detente would ensue, as Germany would settle down to prepare for Barbarossa. Mussolini would most likely pick a fight with Yugoslavia in association with Hungary and Bulgaria (and be successful after some months), with the partition of Yugoslavia (Dalmatia to Italy, Vardar Macedonia to Bulgaria, Voijvodina to Hungary, Croatia-Bosnia as an independent Italian satellite). But again, the third Balkan War is not one into Britain and France would wish to be involved.
Czechoslovakia and Poland would end up as German satellites by a mix of economic and political pressures. What would happen later pretty much depends on Stalin's reaction to the detente between the democratic and fascist capitalist powers. At soem point we may expect a Soviet move on Bessarabia and/or an Hungarian-Bulgarian attack on Romania to recover Transylvania and southern Dobruja, which shall force Romania in the Axis camp.
If he is cowed and stays quiet, the Axis bloc (Germany, Italy, Hungary, Poland, Czechoslovakia, Romania) shall attack him in 1941-42. Britain, France, and the USA would stay neutral, and Japan would most likely backstab Russia. Lack of a second front and Balkan distractions and full access to world trade for the Axis and Land-Lease for Russia would balance lack of surprise for Stalin. Therefore, we can expect a partial Axis victory with a Brest-Litovsk peace of exhaustion in 1943-44.
If however Stalin reacts by seeing Western-fascist detente as an impending sign of an aggressive anti-Soviet alliance, he shall react by pre-emptive aggression, by annexing the Baltic states and starting a row of limited wars against Finland and Romania which will precipitate the formation of an anti-Soviet coalition which shall reverse the OTL roles of Hitler and Stalin. In this situation, Japan has 50% chances of backstabbing Russia (which keeps America neutral) or backstabbing the Euro powers and America in South East Asia (which brings America in the war).