I think you have covered 1066 very well and there are no potential big sellers left. To be honest I didn't find your suggestions very appealing. How many sets would someone buy of the compilation of the Domesday book? I'm finding it hard to imagine what poses you would include. I think there is one area where you could produce something that could be used for 1066 but would be more generic and that would be medieval villagers for approximately 800 AD to 1100 AD. You could do half involved in day to day activities and half suffering a raid and trying to defend their homes with farm implement weapons. I note that some of the figures in your Norman Camp set seem to reflect the Norman harrying of civilians, perhaps in and around Pevensey when they first landed or the harrying of the North after Hastings. You could expand on that. I think the set might sell well as it would have broader applications than just 1066 and could take us right back to the days of Alfred the Great.
I wonder if going back a couple of hundred years to the time of Alfred the Great would be a good next step. Perhaps a set of the normal fyrd which I think is lacking. We need a lot more completely unarmoured figures (helmet at most)using spears and axes and improvised weapons. These could be used for so many different armies, including the Anglo-Saxons at Stamford Bridge, Hastings, Hereward the Wake's guerrillas. Another possible area of expansion could be Irish, Scots and Pictish Dark Age figures, all of whom looked quite distinctive with their garb and equipment compared to Anglo-Saxons and Vikings who despite TV and Hollywood differentiation actually looked very, very similar.
Last point (sorry for the long post) I would also like to support Jerzy's request for Byzantine troops. We already have Muslim soldiers and if you were to add a range of Byzantines then Italy and Sicily could be gamed and this would expand the scope of your Norman ranges.