I wouldn't call current wifi smart any more than I'd call the primitive beamforming in wifi "SDMA." I'd also agree that smart radios need to observe some common set of rules, or at least principles, much in the way that self-driving cars need compatible principles of operation.
I am, however, optimistic about cost and timeline. The amount of hair in your mobile phone's radio to make it work on 2G FDMA/TDMA, WCDMA, and OFDMA, and their respective layer 2 protocols, while it certainly adds cost, doesn't add a multiple of cost compared with, say, a pure wimax 2 radio. Making radios that use different technologies smart enough to share spectrum is a relatively cleaner and less compute-intensive problem. I think it could be done now, and a really huge amount of spectrum could be made available for use cases similar to today's wifi right now.
I am, however, optimistic about cost and timeline. The amount of hair in your mobile phone's radio to make it work on 2G FDMA/TDMA, WCDMA, and OFDMA, and their respective layer 2 protocols, while it certainly adds cost, doesn't add a multiple of cost compared with, say, a pure wimax 2 radio. Making radios that use different technologies smart enough to share spectrum is a relatively cleaner and less compute-intensive problem. I think it could be done now, and a really huge amount of spectrum could be made available for use cases similar to today's wifi right now.