Helped my brother install his next gen Samsung. I checked the resolution for the four available channels. WTHR 1080P, WTHR 1080P, WTTK 1080P, WXIN 720P. The 1080P channels were really sharp.
I don't think you'll be seeing 4K for some time. I would guess that it wouldn't be until 2025 when the first groups of 1.0 stations will likely be shutting down and the sharing markets go back to using their own towers. 4K will need more bandwidth than what 1080P requires. I think that the eager stations may test HDR first before pushing 4K.