The main problem with terrestrial digital TV in the US is the modulation method chosen. The ATSC 1 specs use 8-VSB - which isn't that good for multipath compensation compared to OFDM - which is what DVB-T and T2 use and... DAB/DAB+. That's one reason why digital terrestrial TV works best in the UHF band and with less obstructions in the way. Now ATSC 3 (or Next Gen TV) uses OFDM so it doesn't have that problem ... but then we have the problem of having another transition to another digital format.
As such, the USA could if they wanted to clear out Band I - presently used for TV - and put digital radio in there. Now unlike Europe, the USA broadcasters also tend to own and operate their own transmission equipment. There is not as much mast sharing as there is in Europe. Frankly I don't know the logistics of it, or even if it is feasible... but a build out of a regional digital radio network... With the network operator somewhat separate organizationally from the broadcasters and existing broadcasters having rebroadcast rights on the new digital network.
What I can foresee though is a convergence between public service broadcasting and mobile "phone" service. A next generation system may well be all cellphone service, all Internet, and using more broadcast bands and even satellites to get close to universal coverage. But because this could theoretically make all broadcasts pay to receive rather than free as they are now, the mobile phone companies would be required to zero-rate certain organizations streams in certain geographical areas - like you can grab any mobile phone and call 911 in an emergency, you would be able to grab a mobile data device and watch or listen to certain public media without charge. Mobile phone companies would get recompense by the broadcasters themselves (as they would not need to pay for their own facilities) and possibly government assistance.