Perhaps unsurprisingly, LWN articles on this subject tend to come to the point of view that embedded developers should adjust to fit the kernel developers' model. Perhaps the kernel developers would be able to move towards the embedded developers to some extent without compromising their own positions though?
Just going from the example above (and I realise that this may already be happening without my knowing), the main problem seems to be the interfaces, not the code. So if the embedded developers were able to discuss the interfaces with the relevant kernel developers on private mailing lists, to get an idea of what was likely to wash and what not then everyone would be much further on, even without the embedded people releasing their code.
Of course, once they did get to the stage of releasing code, there would still be the long integration process, but a lot of the heat would be taken off by the fact that the interfaces were likely to get through without too much discussion. The embedded people would be able to ship without the integration being complete, but safe in the knowledge that at some point their stuff would run on a generic kernel, with all the resulting benefits, as long as they showed a reasonable amount of good will.