Funny you should mention Spectrum. Gregg Palermo is a KTVI/KPLR alum; They also appear to have an executive producer, a digital producer, a meteorologist, and a reporter, too. A small team, for sure, but more than KDNL, and it's comical The National Desk.
Studio space might not be an issue. KDNL's old studios at 1215 Cole Street were up for sale last year, as they jumped ship to Brentwood, MO where the Allman Report was being filmed. If Scripps and/or Weigel wants an in town studio that's turn-key, 1215 Cole is it.
https://www.loopnet.com/Listing/1215-Cole-St-Saint-Louis-MO/27232037/
If we are "news saturated" that seems to be news to people here. A quick look at any newscast that KMOV has proves a lot of news is being left on the table. KPLR isn't really producing much of anything, other than essentially a rebroadcast of the previous KTVI newscast. It's leaving KSDK and the Post-Dispatch to find rest of the news out there, but they don't have the resources. We need another functioning newsroom. Spectrum News doesn't really have any sort of obvious presence.