Two questions about the new ATSC 3.0 technology remain:
(1) when will the new television sets be on the market (in the U.S)?, and
(2) will there be converter boxes available for existing sets?

I posed these two questions to the ATSC in Washington and received this reply:

I don’t know when complete ATSC 3.0 TVs will be available but in all likelihood it will be sometime in 2018 considering the complete standard will not be finished until 2017. As far converter boxes are concerned I see something more along the lines of a dongle that will plug directly into an HDMI port or a home tuner/router that will distribute the signal to devices around the home.

Hope this helps...