Interesting, I think I'll steal that synonym for my philosophy exam and see if it'll 'wow' the examiner...'Plato's ditheist thoughts...' - might give it an interesting touch.
Anyway, I think there is a market for any philsophical writing as long as the writer is able to form a convincing point of view, even if it is apparent that Ditheism is really dualism. But I'm sure people would be interested in thoughts that people believe in two Gods (It would still be polytheism when there is two God's) but I'd say Christianity is still monotheistic, Satan doesn't count as a God (Perhaps in other theistic train of thought, as you get a evil Gods) but these dudes would probably not like the idea of Satan being a God and Jesus isn't a demi God, he is practically God as he is a part of the holy trinity, as their belief is that there is only one God, thus Monotheism.