Interesting question! It might have been possible. Although I do think, not being an expert on this by an means though, that there were some cultural differences between Eastern European Jews and German Jews (or even Western European Jews more generally). A Jewish friend of mine tells me that even today in some quarters Eastern European Jews are looked upon as a bit too tribal and "unchill" compared to those Western European Jews. He is of Western European descent, so it might just be the kind of typical snobbism that I suppose is common in all social groups, like how blue bloods look down on those with "only" money etc. Already in the 1800s there were some problems with the ostjuden, according to more than a few Germans from the time.
The poverty of the Ostjuden is a thing of the past by now, though. AFAIK most US Jews were poor when they came here from Eastern Europe but are now one of the wealthiest groups in the US. The same should happen to Ostjuden in this scenario. After all, they are, on average, very smart and talented and thus they should gradually be able to lift themselves out of poverty and into the middle-class or higher if they will have the necessary opportunities to do so.
I'm not sure the Germans would be too happy with all the Jews from the pale of settlement to be honest, at least not if they all migrated into Germany proper.
How ironic considering that the Jews were already the most Germanized people in Eastern Europe other than the Germans themselves! If Germans could only see this, and if the Ostjuden would have refrained from doing stupid things such as supporting Communists, then one would hope that Germany would experience a gradual rise in toleration for Jews like the US experienced during the 20th century in real life.
That being said, I think it is much more likely that those Jews Germanize then that they become Polish or Lithuanian or whatever, for the same reasons that you describe. As for whether or not they could have become German, and how German they could have become... not sure. Maybe things would have been very different without world war two. They probably would have.
Whether or not WWII occurs in this scenario doesn't matter as long as Germany will win it--and it would probably have an excellent chance to do so in this scenario. After all, Germany in this scenario is going to be a status quo power rather than rabidly expansionist (considering that its WWI victory would have already secured a lot of puppet states for it--thus ensuring that Germany will be satisfied and content for a very long time) and thus is probably going to be less likely to provoke large-scale British and American ire and anger.
Perhaps we'd see a German ruling class in Eastern Europe, or in some cases even a Jewish-German ruling class (as I've seen you suggest before in the thread about the Baltics
@Futurist).
Yeah, I mean, Germany could get ethnic Germans from Eastern Europe to help administer its Eastern European puppet states. That said, though, a wider base of support would probably be a good idea--and Eastern European cities and towns were full of essentially German-speaking Jews. (Yiddish is essentially German with Hebrew letters. Surely having Jews learn the Latin alphabet if they have not done so already is not too much to ask for!)
What policies could the Germans enact to make this Germanization happen? Maybe they could implement laws in the occupied territories favouring Germanophones for various roles and lines of work. This would no doubt give the previously largely Jiddisch speaking Eastern European Jews an advantage, and would also create a natural bond between the Germans and the Jews. It would also no doubt antagonize the local Slavic (or Baltic or whatever) populations, but it is not inconcievable that it would be done. Many of the cleverer and more longterm Empires in history have implemented similar policies...
Yeah, that does seem like a good idea--both because it would help facilitate Germanization in Eastern Europe and because it is going to give Jews an attractive option. Basically, Germany would essentially be telling the Jews something like this: "Work with us and you'll live very well. Don't work with us, and we could encourage anti-Semitism among Eastern European locals to shift Eastern European anger against us and towards you! Make your choice!"
Also, such a move on Germany's part might reduce revolutionary activity and as well as reduce support for things such as Communism among Eastern European Jews--which would certainly be a great thing considering that Communism was and is a malignant cancer!
On a wholly diferent sidenote: to be fair some of the Prussian Aristocracy had Polish or Slavic sounding names, even some commoners. Those were not recent immigrants either, but had rather become German in at least the 1700s. That really unpleasant man "Otto Skorzeny" springs to mind for some reason - although I do think he actually had recent Slavic ancestry, so there are some better examples. There's this Juncker familyname I have on the tip of my tongue...
Yeah, this probably isn't that surprising. My guess is that a large number of Slavs ended up being Germanized in the centuries after the Ostsiedlung--hence the possibility of Germans with Slavic last names. Of course, this Germanization probably occurred before mass literacy became a reality; after mass literacy became a reality, Germanizing Eastern Europeans (other than the Jews) would have probably become much harder since the Eastern European peoples would have already developed a national consciousness of their own by that point in time.