CNN.com has a feature on the soon-to-launch series of fan-made audio dramas based upon Trek:
Although there have been made-for-audio dramas based on Trek before -- most notably the two Captain Sulu productions done by Simon & Shuster -- I see this as a promising sign as this is exactly how the Doctor Who audio drama franchise got started back in the days of "Audio Visuals" in the late 1980s. Today there are literally dozens of high-end, fully licensed audio dramas being made by Big Finish, which is for all intents and purposes, Audio Visuals.
Nothing against the fan films, but what I like about the audio dramas is this is the type of medium where you could have Shatner doing a TOS-era Kirk story without any worries about age or anything. There's even precedent for using now-deceased actors. The Big Finish drama Zagreus featured Jon Pertwee, who had died a decade earlier, through the use of archive recordings that were incorporated into the play. It's conceivable something similar could be done with Kelly and Doohan if sufficient recordings exist.