What?
"Try as they might, they can't seem to generate sufficient "wow" with their hardware/Android combinations to muster much brand loyalty and, in return, chunkier profit margins."
Oh please. Samsung, LG and the like can't even manage to code a simple launcher replacement, what makes you think they'd be capable of forking Android and doing a good job of it? Amazon might succeed with their fork but only in using Android as a locked-down but quite-functional firmware replacement - not as a credible mobile OS.
Like it or not, Google do a lot of the heavy lifting when it comes to Android. It wouldn't make much sense for these companies to fork it now. Maybe by "Ice Cream Sandwich" when it's a credible phone *and* tablet OS it will be more forkable as a lot of the hard work will have been done, but right now I doubt it. Plus when they do fork it they need to retain compatibility with the vast number of Android apps available otherwise people will shun the fork like they shun Windows Mobile and WebOS.
Of course if Google starts throwing their weight around with Motorola things might change. I'm sure they're being watched closely. But it's a bit too early to predict the death of the Open Handset Alliance, methinks.