Let me qualify my answer then. I certainly would never suggest a datacenter go wireless. The original question I have an opposing (?) opinion on is "Will companies ever start moving towards using primarily wireless networks?" and to that I say yes.
The wireless of yesterday is rapidly changing. Take a look at what Bluesocket is now doing with moving the management and control planes to a virtual machine that can hosted in the cloud (http://www.bluesocket.com/media/2010-07-05_vWLAN_Whitepaper.pdf
), thus providing hot-swap redundancy. I absolutely can see "companies [...] moving towards using primarily wireless networks" though I should disclose that I'm one of the crowd of people trying to make that happen.
Done properly, a company can save a lot of money by going wireless in many circumstances (but not all)
and network designers planning for the future should absolutely take wireless into consideration as the growth of devices, especially in the hospital arena, explodes. They are one the biggest drivers of these advancements as they have expensive devices that need to be mobile as well as tracked so staff always knows where the closest infusion pump or EKG machine is.
re:"There is always going to be interference in the 802.11 space unless you're in a bunker."
I would say that very well depends on the building and what type of corporation you're talking about. If you share office space with others in a building, yes you definitely will have interference. If you own the whole building and sometimes the whole block, ehhh...not so much. By entering some properties, you are absolutely not allowed to bring up your own AP and a WIPS should catch that immediately and someone carrying a gun is quite likely to put you through a lot of hell. Pointing your 'cantenna' at some target is going to do you little good if the company is using 802.1x and other security measures.
re:"I couldn't fathom moving our erp system to the cloud. Or moving a critical industrial control system to the cloud.... That's crazy talk."
I'm not suggesting you do. I'm not painting broad strokes here, suggesting that all companies should move to wireless. I can point out a thousand scenarios where that would be a bad thing but OTOH, I can come up with a thousand where it does make sense. We do a lot of apartment complexes and I can say unequivocally that it makes a lot of sense in that environment.
And I'll repeat the point I made earlier that your security is rarely as good as most admins think it is, as the video points out it can usually be defeated very easily.