Note that a portable ATSC television - IF it's not moving - works just fine if it's in reach of the notoriously finicky digital signals from the ATSC transmitters.
I was just watching a TV commercial for ATT's U-verse video service on smartphones, laptops, etc. Any 3G/4G video service will likely be overwhelmed during some large scale emergency where many people are trying to stream video, so that's certainly a survival-related application where a broadcast technology like Mobile DTV would shine. Rolling down the freeway evacuating from a hurricane or otherwise bugging out would be two examples of situations where 3G would get bogged down quickly if many people in those cars were using the service at the same time.
From the Mobile DTV technical descriptions, it seems to use additional error correction plus a lower bandwidth signal, making it quite robust. I don't know, does regular digital TV pixelate in heavy weather like my satellite TV does? I haven't been around really bad weather since broadcast TV switched over to digital, but if it does, that's another plus for Mobile DTV. It's not 1080p high-def, but who needs that in an emergency situation?
The "burst" capability of Mobile DTV (if I'm reading the descriptions correctly) is also intriguing to me. If electricity is scarce, either on the transmitting or receiving end, seems like you could use this capability to download news updates as fast as possible and lets you watch it when you want, say when power is more readily available.