Given the standard of living differences, it would take large incentives. There were also some cultural differences as well. A certain number of the Prussian Poles were members of Polish subgroups with varying degrees of German cultural influences. In the case of some of the smaller groups, this included adopting Prussia's Lutheran church.
In short, though Kashubians and other groups identify as Polish and would have preferred a Polish state, they could well of tilted strongly to Germany if the choice was: German possession vs Russian possession.
True. Poles in Germany can roughly be split into Posen Poles, Westpreußen / Ermland Poles, Silesian Poles, Kashubians, and Masurians.
Posen Poles don't exactly "like" Germany, and might leave if given the chance. Same goes with a small section of West Prussian ones.
Most of the latter, as well as Poles from Warmia and Silesia, however, keep their Polish identity but have no desire to leave.
Kashubians have their own language, and would identify themselves more likely as Kashubians than Poles.
Masurians identify themselves as Germans who can speak Polish. They also are Protestants as opposed to Catholic Poles.
