It's doubling of powers though. Just going from 8 to 9 would increase it by 36 fold. Not sure what I'm missing here but there should be about 2.8 trillion combinations of 8 character lower alpha + digit
= (26 + 10) ^ 8
Just going to 9 characters gives you 101 quadrillion possibilities, which grabbing my not really Bill Gates hat ought to be enough for anyone.
I don't follow what they are running out of because these are already big numbers. . My suspicion is that they are concatenating more info into those identifiers (first x characters means y, etc) but that's just a guess.