I don't think it'll close anytime soon.
The grosses since 2003 have rarely gone over $550,000, and it has spent a big bulk of the time pulling in grosses in the $300,000s and $400,000s. It had one peak week in 2006 of approximately $665,000, and that is one of the highest it has ever reached. This was around the Christmas/New Year's Eve season weekend.
Avenue Q is cheaper to run than most other shows, so for its size, it is pulling in a decent amount.
"We like to snark around here. Sometimes we actually talk about theater...but we try not to let that get in our way." - dramamama611