MulderI don't know. Think there was still a lot of separate identity in areas such as Saxony and Hanover. Also there had traditionally been a fair amount of tension between the Prussian Rhineland, predominantly mercantile, liberal and Catholic and the eastern heartland, dominanted by the military and agrarian interests. It might be too late by this time but I think there's a decent chance of it working. Don't forget its Prussia rather than Germany as a whole blamed for the excesses of the war and only Prussia paying the markedly reduced level of reparations. If the various states can avoid the economic and political burden I think there would be a decent amount of support in a lot of areas. At least to make any reunification less dominated by Prussia and a revived military simply because there would be even more concern about a new war in a country with less certain unity.
I really think you're drastically underestimating the strength of German national feeling. The comradeship of war erased local differences (by analogy, the development of Scottish nationalism completely stopped cold in Britain during the wars), and all the seperatist movements of 1918-1919, as Mulder points out, were laughable. Austria, of course, tried to
join Germany in its hour of defeat.
How would this work, logistically? Nothing is going to convince anyone to just secede because the French say so. Germany will have to be occupied, which as far as Britain is concerned is a humungous waste of time and resources (and Britain wouldn't see a fragmented Germany as in its interests either). So this plan required France to invade every portion of Germany they want to carve off, assemble a government (I highly doubt they can get any immediately elected government to support a seperatist program) by themselves, which is of course not going to make them popular, meaning they'll basically need to occupy large parts of Germany under the guise of collaborating governments indefinately.
If you want to deunify Germany and keep it that way merely have German split up into four different countries and occupy them until reparations are paid.
Again, we can't just conjure up "four countries". We'll have to put boots on the ground to make it happen, as if the Ruhr imbroglio wasn't divisive enough, or didn't meet enough resistance from the Germans. We'll have to establish governments which will be effectively ocucpations, since all the creative accounting in the world isn't going to produce a democratic seperatist administration in any quarter in Germany. And we'll have to prop them up as long as we want them to exist.