If Prey was getting the audiobook treatment, and assuming the process is similar to what we went through with Legacies, then JJM would've likely already have been working with someone at S&S Audio to nail down pronunciations of all those crazy Trek words and stuff. And I'd think the first book and perhaps the second one would've been recorded by now.
I'd have to look at my emails to see what sort of lead time we were working with on the first book. I know it was a decent but not a huge block of time.
To answer the OP's question, I've not yet heard anything about sales numbers for the Legacies audios. Here's hoping.