Case in point, two casualties just this year:
Pickler & Ben was a show that was launched by Scripps, exclusive to their O&Os, distributed by Disney, with a CMT cable deal and a shopping deal with HSN. And even with all that, it only lasted 2 years.
The Steve Show, hosted by Steve Harvey, also lasted two years. It was the successor to his Chicago-based Steve Harvey show that ran for 5 years. It will be replaced by The Kelly Clarkson show. That show will be run on all NBC O&Os as a lead in to Ellen.
Looking back a year:
Harry: Hosted by Harry Connick Jr. Lasted 2 years
Anderson Live: Hosted by Anderson Cooper, lasted 2 years, from 2010-2012.
So yes, there have been a lot of these shows, but they tend to only last a couple years, and get replaced by something else.