Do you think the next pro body will be called D4? I'm been thinking about this as i have been travelling in souteast Asia quite a lot and can't remember a singe elevator with a fourth floor. They always goes from floor three to floor five, and the same thing from 13 to 15! This is because the number four sound like death an is considered as bad luck...
You may be onto something here. Perhaps Nikon will be forced to abandon the naming conventions we have become so used to.
I can remember some of the model names of Japanese cars that just would not work in the US (bird and flower names spring to mind).
Perhaps they can use different model names in different markets. The D4 in western countries could be the D6.437 (using metric length conversions). Or perhaps the weight could be used as the model number.
My personal favorite would be to use a name, and the appropriate translation to other languages. Maybe the Nikon Bob (or Tom)? As the level of complexity of the camera increases, the name could reflect that. Most of us might be challenged by the Nikon Beelzebub.