What if Germany only conquers the Danzig and the Polish Corridor to unite East Prussia with Germany and does not attempt to conquer the rest of Poland or any other countries?
And leading up to the war Germany has sensible economic policies that do not require permanent war or a slave driven economy.
Would Poland, the United Kingdom and France continue to attack Germany?
The bit about sensible German policies, without adequate explanation of how Germany proceeds with its conquests, is impossible to comment upon without details on what those policies are and how they impact Germany's behavior and expansion, so I'm going to assume Germany goes as OTL until the aforementioned change of plans concerning Poland happens in 1939. (This would be possible, but preventing Hitler from starting a world war is only possible by killing him. I assume he survives. If this scenario avoids Hitler being in charge of Germany the amount of possibilities makes it all but impossible to comment upon constructively without more details on what happened.)
Of course Poland would continue to fight. After all, Germany has just invaded its territory. But describing this as 'continuing to attack Germany' is a decidedly ... imprecise ... phrasing.
The UK and France in all likelihood declare war, but will make zero attacks, as in OTL. (Bad jokes like the RAF dropping leaflets or the so-called Saar Offensive do not count as attacks.)
Would a peace treaty eventually occur? What actions would the Soviet Union, The US, Japan and Italy take in this situation?
How would this effect the Cold War?
Stalin will invade Poland shortly.
With the altered German mindset in this scenario I suppose it might be possible for prolonged western inactivity following the delay caused by the German halt in the attack to cause Poland to surrender. With "Vichy Poland" having exited the war, a "Free Polish" government is formed in Paris.