We're possibly running across a terminology clash?
From Wikipedia:
A trillion is a number with two distinct definitions:
1,000,000,000,000, i.e. one million million, or 1012 (ten to the twelfth power), as defined on the short scale. This is now the meaning in both American and British English.
1,000,000,000,000,000,000, i.e. 1018 (ten to the eighteenth power), as defined on the long scale. This is one million times larger than the short scale trillion. This is the former meaning in British English and the current use in many non-English-speaking countries.
I'm pretty sure there isn't a long trillion in the whole game's economy, not even on Live.
But: If each of your 1000 character slots is occupied with a character holding 100 Billion (via the AH trick), you would only need 10 accounts to hold a short trillion.
Doable, if only just. Probably wouldn't get much playing done, though!