In Orlando, where Cox also has a simulcast AM-FM Talk format, they eventually converted the AM station to Sports. But in most other markets, Atlanta, Jacksonville, Tulsa, etc., Cox has kept the simulcast. So my guess is they'll keep 1290 as Talk, because the FM signal licensed to Piqua doesn't fully cover the market.
It's true that when you have a simulcast, some stations forget about the AM. A few AM stations that have a low-power FM translator now give the FM's frequency and forget the AM's, even though you can't hear the translator more than 10 miles from downtown.