Doubtful. The French would have an interest in keeping the Rhineland non-German (though admittedly, they'd LOVE it to be French, but that ain't happening on Britain's watch) and even if the Germans and French did this the British would have a heart attack over it.
German unification was in the interest of exactly one great power- Prussia- actively harmful to two more (Austria and Frqnce) and a very mixed bag for a fourth (Britain- on the one hand they don't like the competition, OTOH Germany is a useful stick to beat France and/or Russia with a la the Seven Year War.) Ironically Russia was not, strictly speaking, innately hostile to Germany- they had a shared interest in stopping Polish revanchism, they both might get into conlfict with Britain. Conflicts in the Baltic are a possible sore point, and insofar as they would both like to control the Balkans if not Europe they would probably compete, but there was nothing within Russia's geopolitical outlook that mandated the vehemence of the OTL 20th century. It was the defeat in the Russo Japanese war, and the subsequent resurgence if Europe-oriented parties in the czars government, that really hardened attitudes. Nevertheless give it another few years and one could have imagined Britain drifting away from her Pro Russia policy out of fear.
Regardless, for the prompt in question I do wonder whether German unification would happen at all. In a scenario where Prussia possesses most of Poland or is extremely weak, and does not own the Rhine, would she still support the nationlist project? I think not.