I guess the question is, are these audio books actually successful? If so, presumably there would be more.
Also, presumably Titan is aware of how popular Cold Forge is. So one would hope that would be the next book go get the audio treatment.
I've always been of the mind that authors and artists should take their time and put out a better finished product. Cold Forge is a longer book so it would stand to reason that it takes more time to produce the audio version. My two cents.