As a result of France and Britain's appeasement policy, Hitler got away with a lot of small aggressions throughout the 30s. Did the Nazis think the same would happen again? Did anyone think they could get away with a slap on the wrist? Were there any high-ranking officials that thought contrary to the popular opinion?
Not only did they realize it, they outright expected it. Hitler had already planned to fight a war against France and her Eastern European allies (Czechoslovakia and Poland, and whoever else may want to test Germany, like Romania) before he become chancellor. Interestingly, Hitler in the early 30's thought that war with Britain may be avoidable; he was led to this belief by the conciliatory actions of Britain in the 1920's, including the Treaty of Locarno, where Britain supported the restructuring of Germany's debt in an attempt to create cooperation between France and the Weimar Republic. However, within a few years of becoming chancellor, Hitler came to the conclusion that war with Britain could not be avoided and began to plan for conflict with both. Ironically, this is because of the British policy of appeasement in the 1930's, whereby Britain kept drawing very distant lines in the sand; they were still lines in the sand, after all, and sooner or later Hitler was going to take a step too far.
There are reports of Hitler being furious that the Allies didn't 'take the bait' with Czechoslovakia, although several of his generals famously were ready to plot Hitler's assassination if he had taken Germany to war over the Sudetenland. He expected this to be the first of several wars Germany would have to fight because he desired a period of peace between defeating the Allies and invading the Soviet Union. After the Soviet Union was defeated and turned into more lebensraum, Hitler expected to fight a third war against the United States. This was to be primarily a naval war fought in the Atlantic, meant to subdue the United States, economically crippling it and forcing the United States to accept German economic hegemony. These wars were meant to be fought throughout the 40's, with the final conflict taking place closer to 1950. However, strategic necessity made these general war plans invalid, as Hitler and the German military felt that its best chance to defeat the Soviet Union was sooner rather than later, and so they invaded in June of 1941. And obviously, the military alliance with Japan dragged Germany into war with the United States in December of 1941, although from my reading it doesn't seem that Hitler was personally very intimidated by the prospect of the Americans joining the fight.
Your question also asks about anyone thinking the Germans could get away with demands made against Poland, but I am unfamiliar with the biographies of the German military staff that might have dissented with him. Obviously, the pacifists throughout Europe thought Hitler very much should get a slap on the wrist, and nothing more, but I am not familiar enough with the opinions of anyone in positions of power in Britain, France, Germany, or elsewhere who truly believed Germany would not be challenged for its aggression against Poland.
Source: Weinberg, Gerhard L. Germany, Hitler, and World War II. Cambridge University Press, Cambridge. 1995.