I wonder, will demographics also be reversed? Meaning that Europe will have the world’s highest population? The only way that could be achieved is if the Romans control not only southern, central and western Europe, but also eastern Europe (especially Ukraine and the Volga region), so that they have enough fertile land at their disposal to feed a population of several hundred million people (IOTL China had around 300 million people by the 18th century). I don’t think pre-industrial Europe could support the kind of population density that China or India had historically, so they’ll need quantity over quality. If eastern Europe had the same population density as western Europe, then a modern European population of >1 billion could easily be achieved.
As for East Asia, if they start modernizing and industrializing a century or two earlier than OTL, then their population growth will also slow down much earlier, which means by the 20th century they’d have a lower population than Europe. Though that leaves me wondering about India. Will they also start to modernize earlier due to their proximity with East Asia, or will they be more an equivalent to the Ottoman Empire; the ‘Sick Man of Asia’, basically? If Japan is this TL’s version of Britain, I guess they’ll be the ones to colonize India.
