But that will not be set in stone. Any new artist could show up and blow us all out of the water. FOR NOW, it's Gaga.
To outdo Gaga's 110 million records in 4 years... I would be highly impressed with that person, but I highly doubt that there will be such a person in the near future.
It's undeniable. No other current artist comes close to the amount of impact, popularity or anything else. The crowds a numbers she is able to pull alone, no other pop girl is doing it.