Making HD radio mandatory for smart-phones is impossible, otherwise they would be trying to that instead of FM. They want mandatory HD radio in phones far more than plain old FM, but they cannot force the companies to pay the IBOC license fees. If it were an open standard, possibly they could. As is, they can't.
In a perfect world the streaming/HD radio hybrid would be great. Unfortunately, streams always have lag behind the actual broadcast. It would be extremely difficult to synchronize the HD/FM/stream. Not to mention bufferless streaming is not wise because without a buffer, the slightest drop in signal would render the stream gone. It is a great idea, but actual implementation would be very difficult.
Regardless, there have been rumors next gen Iphone/Ipod touch may have HD radio. Possibly even the nano. If that were to happen, HD radio usage would surge. However these rumors are nothing new and reappear every so many months. The fact that Apple did apply for patents relating to HD radio within the last 6-7 months does cause some reason to wonder though.