Let's say that the wars of the 16-17th centuries weren't that much destructive and most of the depopulated territories could be resettled with the ethnically same population, which lived there prior by the end of the 18th century.
By 1800, the population of Hungary (including Croatia) exceeds 10 million out of which ~70% is Hungarian, ~10% is Croatian, ~6% is Romanian, ~5% is German, ~5% is Slovak, ~2% is Serbian and ~2% is other.
What happens next? What changes?
Tell me what you think!