It's not completely inconceivable that Poland and Germany would have allied, during WWII Germany was allied with "Slavic" nations like Hungary, Romania and Bulgaria. Poland even partook in the dismemberment of Czechoslovakia in 1938, annexing parts of it. I think a bigger stumbling block was that Hitler viewed the parts of Poland Germany lost after WWI as rightfully German territory, something that can't be said of e.g. Romania.