1) The quote from Lenin, "_Kautsky detaches the politics of imperialism from its economics_", reminds us that Lenin's pamphlet, too, did the same out of (apparent) necessity, in order to get "Imperialism" past the Czarist censorship for distribution in Russia. This Lenin documents in the post-1917 editions of the pamphlet. This is a caution against literal readings.
2) Thus using Hilferding's model was not a misreading of the trajectory of capitalist development - the War was not over yet at the time of the pamphlet's publication and it was not certain that Germany would lose. In other words, the "valid" model was determined by the results of the inter-imperialist rivalry. The "mode of articulation" of finance and production is a secondary question - one could just as easily plug in the "American model" of largely self-financing corporations into Lenin's framework, and it would still be valid.
3) The geopolitical form of imperialism has changed, of course - not least the collapse of the old territorial empires of classical modern times - but the basic framework remains the same. What we have today - and have had since the end of WW2 - is the "singularity case" of Lenin's "Imperialism", where a single security structure replaces multiple competing security structures. Nevertheless, the singularity is a necessity for the whole structure. The difference devolves into that of a periodization within Lenin's concept of imperialism: We live in the period of "monopoly imperialism" which, moreover, is also an absolutist imperialism - Washington as absolute monarch with special, exclusive rights of seigniorage, such as the ability to run up mammoth trade deficits forever, seemingly in defiance of the "laws of economics", for example. It is absolutist because, although it is theoretically possible (precisely in the Kautskyian sense) for another single or group of imperialist states to take over Washington's role, it is in practice impossible to see how any of the existing powers could do this, in the indefinite foreseeable future, i.e., there is no such prospect. The other powers know this and that is why they are willing to sacrifice their own immediate self-interest when it involves the security and political stability of the United States. This is the fundamental condition that must be recognized in any explanation of why Japan has been in a 10+ year long stagnation, for one salient example.
4) The absence of a revolutionary working class party (to phrase it broadly) today, demonstrates that we were not able to successfully "retreat in good order", and have been instead thrust back into a period of regroupment similar to that of post-1848. However, instead of taking responsibility, some, perhaps on the basis of their own bitter experience with these failures, have tried to escape this responsibility by rejecting the project itself. Especially here in the U.S., where egoistical projection and blaming others is such a wonderful cultural trait.
-Brad Mayer Oakland, CA