Why would ATSC 3.0 bring back Lo-vhf from the dead?
VHF-low isn't dead, its just pining.
There are markets that are going to be using all but one or two of the VHF-low frequencies after the repack and those markets represent a lot of eyeballs. It looks like the LA market may be using all five VHF-low channels.
The ATSC 3.0 stations that are brought online will have to use frequencies that aren't currently in use by DTV. In many markets, that's likely to mean visiting VHF-low. Only after Next-Gen takes over can they return to UHF bandwidth (assuming they feel the need to).
Because Next-Gen isn't mandated, the stations can't just bail on their DTV broadcasts and hope that everyone will upgrade their TVs overnight. Let us never forget the lessons of the mandated DTV conversion and how they might apply to a non-mandated conversion.
Many DTV stations are sufficiently loaded with channels now that the lighthousing concept isn't going to net them the bandwidth needed to put more stations on a single channel unless they convert the HD to SD and that will surely force viewers to use other methods of viewing.
It has been my long-held opinion that if Next-Gen doesn't deliver on the upgraded features (UHD, "immersive sound", etc.) because it is too crowded with subchannels, people won't voluntarily upgrade. The prevailing theories hold that, at least early on, Next-Gen will be limited to just one channel where "premium" UHD (UHD with HDR and WCG) is involved. There are many shapes and sizes of promised chickens (including HD with HDR and WCG) and we haven't seen any eggs yet.