Given that humanity's track seems to be toward ever greater diversity, it's hard to imagine we'd become a one-dimensional archetype species.
In the past, humans were naturally diverse simply because there were so many distinct communities that hardly ever interacted with each other. Nowadays you might be exposed to many times more diversity than the average medieval peasant ever was but there's nothing contradictory about that happening as the total amount of diversity in the world continues to decrease.
Perhaps we'll settle on one culture as we choose the best one. I more imagine we'll end up with one culture in an endless echo chamber, forever unable to sense our own biases.
Isn't that the whole point of the Borg?