Well, G is for 1 billion, so it'd be billions of times worse.
1024 would be kB, which wouldn't then be GB.
Unless you believe in the multiverse, in which case they already exist in all permutations, every second of every day, and thus far exceeds even a TB and even a personal best (PB).
Incidentally, just as "g" is excluded as a prefix because it is the symbol for grammes, "K" isn't allowed because it is the symbol for the Kelvin temperature range.
Thus kilogrammes are denoted by kg.
OK?