The failure of podcasting? I think perhaps you are confusing your terms. There is a difference between a medium failing and a medium without a business model. As Seth Harwood recently said in an interview I conduced with him on Google video, as yet there is no business model for podcasting aside from, occasionally, selling ads to defray costs, and (for authors), building enough of a buzz to make a run at Amazon's bestseller rankings and attract big publishing deals. The rest of podcasting is still looking for a business model, no doubt about it.

The problem with your article, Ian, is that you're looking at podcasting through the lens of radio.
Podcasting is not radio - the radio format as it exists today is based around three practical realities:
1) radio production has historically been stratospherically expensive
2) after the advent of television, radio's audience profile changed and long format fiction and similar in-depth long-form interest shows lost audience, while music and short-segment interview and news shows gained audience share.
3) as a consequence of number 2 and an increasingly transient urban population, the programming on radio - particularly talk radio and talk/music hybrid programs - must reflect the rhythm of the workday to remain lucrative.

Because of this, over the last forty to fifty years the radio business has consolidated around the commute rhythm - exciting, ostensibly edgy content in the morning drive time giving way to banal, background-noise content that demands little from its audience for the duration of the workday, and back to a more laid back but engaging format at the end of the day.

But podcasting is not radio, nor should it be. Although it does work as an excellent way to time-shift radio programs, it does something far more useful and important: It provides a platform for a variety of formats and format experimentation, from underground music programming to the miraculous resurrection of the once-dead-in-the-U.S. radio drama, to the innovative loss-leader distribution of fiction innovated by Mark Jeffrey, Tee Morris, and Scott Sigler. There have also been a number of other formats tried with various degrees of success - audio blogging, a'la "Tag in the Seam," business tutorials, a'la The Survivor's Guide to Writing Fantasy and Answers for Freelancers, and, of course, there are a lot of formats and podcasts that simply don't work. The low barrier to entry means many - perhaps most - podcasts will never make it past a few episodes, or attract more than a couple dozen listeners.

Will podcasting find a business model? No. What will more likely happen is that different sorts of podcasts will find different business models that work for their targeted demographic. Some will doubtless be advertiser supported, some will be hobbies, some will be loss-leaders, some will be
maintained by patronage and swag sales, and there will probably be a few more ideas rolled out by innovative podcasters over the coming months.

So, Ian, I think that your thesis is flawed from the beginning. Podcasting is not failing. It is merely failing to be radio.