And a way to drive viewership? Make a half-hour or hour long show to syndicate on their stations. It could follow the "PM/Evening Magazine" model. Have a bank of stories that are chosen and promoted, and that drive viewership to the main channel. It could be localized in the larger markets, especially if it's a story that originated locally or in the region.
And if all else fails, see if CNN still has the "jukebox" they used for Headline News in the 90s. Call me old fashioned, sometimes I just want to know what's going on at a random time....
And when HLN jumped the shark, the last days of the All News Channel was a good watch. They essentially did what Nexstar should have been doing all along. Using THEIR stations to present content to a national audience.
We have to remember when NewsNation runs a story from one of Nexstar's markets, that local reporter doing the story is mentioned on-air as a "NewsNation reporter." So, if (let's say) a report on the recent blizzard runs on KDVR/KWGN in Denver (both Nexstar stations), that reporter on said station will most likely first use their station's mic flag for the local run, before using the NewsNation mic flag for the national run of that story. (The story, BTW, would probably air first locally before airing nationally.)
It may sound kind of corny, but I tend to think Nexstar is also using NewsNation as a showcase for all the journalistic work done by reporters all across the Nexstar station spectrum. If one is a reporter at a Nexstar station and he or she is chosen somehow to file a report for NewsNation, this would be considered a major honor/accomplishment for that reporter. (Scripps sometimes does the same thing with Newsy, in which reports from some of their stations also air at various points on the channel's programs.)