Hardware availability and Audio improvements too, hopefully
Depending on the speed with which manufacturers can ramp up H.265 chipset production it would not be long for USB and set top box products to take to market. It was inevitable that ATSC's MPEG-2 would become obsolescent, but skipping H.264 (MPEG-4) for H.265 would make for a whole new hardware market, and of course a selling point for new OEM HDTVs.
I would presume that a similar technological jump in OTA audio modulation would also happen, with common broadcast of DTS, TruHD, 7.2, etc. etc. formats via OTA.