A public speech to suck up to Hitler and sound tough to the public is not really what he actually thought. Hitler was all about "fuck sustainable economics, we're going to war bitches!" and Goering was maintaining his political position and power by being Hitler's handmaiden, so it is hardly surprising he's echoing what Hitler himself was saying and wanted to hear...because that was what was rewarded by Hitler. When Hitler is out of the picture and Goering isn't about going to war like Hitler was its a lot more likely that Goering out of necessity to protect his regime actually has to focus on sustainable economics. In fact without the entire reason for the unsustainable economic policy, Hitler's planned wars of conquest, there is no reason to maintain that unsustainable economic policy.
Goering's actual historical statements and actions say otherwise. There is no evidence that Goering understood that the reckless armament drive would lead to Germany's ruin unless Germany plunges into war. Furthermore, Goring's opposition to war while continuing to support the economic campaign is evidence against the idea that he was simply saying what Hitler wanted to hear, otherwise he. Goring was loyal to Hitler, but that didn't mean he simply regurgitated the Fuhrer's policies. As a case in point, the speech I quoted was directed at the army, not Hitler. You tried to portray his negotiations with Britain as such, but the topic of the German economy never came up in those. Those negotiations were about trying to avert an impending war over Poland because Goring wasn't sure Germany could win such a war despite the reckless rearmament, economic matters weren't discussed at all. But being unwilling to plunge into a extremely risky war is not the same thing as being unwilling to continue a massive rearmament scheme that Goering himself was heavily responsible for. In fact, it's far more likely that Goering continues rearmament until it's too late for the same reason you posit he'll abandon it: because without the longer-term risk being apparently to him, in the short-term it seems to ensure the protection of his regime. Firstly, by providing legitimacy to the masses due to the perceived economic benefits as well as propaganda value of it making Germany seem big and strong. Secondly, by ensuring the support of the German military who didn't understand sustainable economics any more then the Nazis (and in fact understood it less then Hitler) did but understood that the rearmament program made them really powerful and important and would likely object to any attempts to end it, particularly given the unavoidable accompanying economic pain that would come with it, would invariably give them the perception that Goring was undoing everything Hitler had given them and so Goring must be removed for the good of Germany (and themselves).
Of course, in the end the military might end up later overthrowing Goring anyways to prevent an unwinnable war in 1941 or '42 after the economic troubles catch up with them. Whether they'd then attempt economic normalization (presumably after consulting with leading German economists on the
how since, as I observed, the German military had even less economic sense then Hitler) while blaming all the economic pain (which would already be existant by then) on the Nazis or try to tough it out through some other measure until the German people revolt or unhappily muddle along... well, that's harder to say.
Basically, the two most likely outcomes of Hitler dying in '38 remain either a last-gasp war that Germany loses harder then the OTL one or the German military overthrowing the Nazis to prevent said war.
Not necessarily; though this is perhaps just a difference in perspective on my part, I'd argue that if you stop at Munich (for whatever reason), the Nazi government will still have enough of its trustworthiness in check that the changes in the Eastern border can still be reguarded as (acceptable) rectifications to the Treaty of Versailles in line with the idea of ethnic German self-determination. Though its certainly not guranteed, there's a statistically significant chance that a Goering government could reach a detante with the West; particularly if Stalin starts making troubling moves in the direction of the East German states in line with perceived German weakness in his goal of establishing an expanded sphere of Soviet influence.
The evidence says otherwise. The trade wars since 1936 had alienated Western economic interests and the Anglo-French had begun rearmament in earnest in response to the Germans own program. Appeasement was partly built on buying enough time for that rearmament program to mature, since Germany's earlier start currently gave it a military advantage. Had the Anglo-French still had the degree of trustworthiness you are claiming, they would not have objected so violently to the invasion of Czechoslovakia in 1939 and then declared war over Poland. Finally, Stalin acting so aggressively without the other major powers already distracted would be royally out of character for him and amounts more to wishful thinking then honest examination of the alternate history scenario.
But even handwaving in western cooperation, that doesn't change that ending rearmament would mean economic pain on a scale too unpalatable to the Nazis leadership to make it a likely option until it all explodes in their face. As I said, the projections were on the order of 2-to-2.5 million unemployed, among other horrible short-term effects and that was in 1936 with Germany in a better
domestic position for ending rearmament as well as international. In 1938, the accompanying figures would be orders of magnitude worse as much more of Germany's civilian industry had basically been chopped up and thrown into the flames of armaments.