Emily Gordon writes:
The blog Instant Tea, part of the Dallas Voice, asks the same question, as does the Washington Post, in this live chat exchange (the questioner is not, I assume, anyone from the actual show):

Avenue Q: Do the producers retire its “Gary Coleman”?

Hank Stuever: Hmmm. Good question. Get me rewrite. There are so many living, washed-up tv stars to sub in.

Maybe our friend Ben Bass can provide some insight, since he knows the folks behind the musical. Having reported a rejected Talk of the Town piece back when Obama was elected, about whether the line “George Bush is only for now!” would be replaced (they decided to keep it), I have a hunch they may hold on to the Gary Coleman character, too.

Besides, how many leading parts for black women (Coleman is played by a woman; in New York, currently by Danielle K. Thomas) are there in high-profile, touring shows? Not that many. I vote to preserve Coleman’s memory in this highly affectionate, vibrant portrayal of what his life might have been if he’d taken another path. Till our dreams come true, we live on Avenue Q.