It has very little to do with the longevity of shows, and plenty to do with station groups opting not to buy syndicated programs for certain timeslots at all.
The Indianapolis market has many fewer hours of syndicated programming in its daytime schedule now than it did 10 years ago.
WTHR (NBC) has basically the same schedule they have had for 20 years.
WXIN (FOX) used to have 3 hours of morning news, now it has 6. It used to have no local news in the early evening, now there's 3.5 hours. And they didn't have an 11pm newscast either. Grand total of 10 hours fewer each day.
WRTV (ABC) has cut 2.5 hours of studio syndication by adding Scripps's "Right This Minute" and 4pm news and 7pm news.
I'm sure WISH had at least one fewer hour of syndication, on account of the IndyStyle program they produce locally.
WTTV's affiliation with CBS caused another net loss, because WTTV did not previously have a newsroom. WTTV airs 4.5 hours daily of news.
These 5 stations eliminated 18 hours of studio syndication daily. Much of which was trash talk, court shows, or reruns, but some of it was the kind of first run talk shows and variety shows this article discusses. I'd guess 3 or 4 hours worth.
Well, that's 3 or 4 hours of programs that don't need to be produced by the studios.