An assumption could be that Poles would have been moved to the East or work as servants in the GG (General Gouvernement) district, with young Polish kids sended to germany to be re educated
How optimistic of you."Unfortunately, a policy towards Poland, whereby the East was to be Germanized, was demanded by many and was based on the same false reasoning. Here again it was believed that the Polish people could be Germanized by being compelled to use the German language. The result would have been fatal. A people of foreign race would have had to use the German language to express modes of thought that were foreign to the German, thus compromising by its own inferiority the dignity and nobility of our nation. It is revolting to think how much damage is indirectly done to German prestige today through the fact that the German patois of the Jews when they enter the United States enables them to be classed as Germans, because many Americans are quite ignorant of German conditions. Among us, nobody would think of taking these unhygienic immigrants from the East for members of the German race and nation merely because they mostly speak German."
Adolf Hitler's words (on the subject of Germanization of Poles during the time when Poland was partitioned)
Hitler would never accept 're-educating' 30 million Poles not to mention the fact that lots of German rulers tried to do that before and failed. Even if the Nazis were willing to try, it wouldn't have been successful - there were simply too many Poles. A nation of 30 million can't be easily kept in check and certainly won't willingly give up their children.
Nazis also sucked at expulsions. They weren't even able to resettle 100.000 Poles from one area (Zamość) without sending most of them to concentration camps. And if they'd won, then Poles wouldn't have been the only Slavic nation under their control. I highly doubt that Hitler would want 100 million Slavic brats running around Germany. The whole POINT of 'racial hygiene' was to PREVENT foreign blood from polluting precious German blood.
So, sooner or later the Nazis would have been forced to try physically reducing the number of Poles through the means of mass murder but that, too, would have failed. It's simply impossible to exterminate a whole nation of 30 milion without anyone noticing or resisting. Eventually, Hitler would've been forced to tolerate the Poles, but the relations would remain awkward and hostile.