RNN owned stations run the “coming soon” loop on unleased subchannels, regardless of whether there is actually any program service about to launch. Here in Houston, co-owned KUBE has been running the “coming soon” loop for many months on its .2 channel.
DFW, like Houston, might be at a saturation point for the number of available full power subchannels. I’m guessing that a number of programmers are going with the presumably cheaper rates on LPTVs.