Without smallpox et al., it very likely would not have happened at all. The settlers/colonialists would have faced a massively larger existing population, and would almost certainly have lost the violent struggle. There would still be people of European descent in the Americas, but not as part of the dominant culture.
The Aztecs could have picked up tech like gunpowder and horses in a few decades and easily kept the Spanish out of their home turf, if 90% of them hadn't died from Smallpox and Maasles.
I don't know if you're being sarcastic or not, so just to clarify ...
it is absolutely a different claim. The land was not empty at all, though it did have millions less people than it had had a century or two earlier. Ethnic cleansing by violence was absolutely a central part of the expansion of the US (and also New Spain before it). The only difference is the question of whether, in a violent struggle between the American peoples at their pre-smallpox population levels and arriving European settlers, the latter would have won (and with relative ease). My point/claim is that they probably would not.
