Considering that Cumulus is shelling out some serious money for this station, they're going to do a format that will get listeners, attention and money.
Forget moving WABC to FM. They need to sort 770 out first. And with them likely losing Rush and Hannity to WOR eventually, what would they put there? I'd rule out talk.
Forget all-news. Merlin is still licking their wounds after trying to take on CBS.
Forget CBS Sports. They're not spending all that money to be the 3rd place FM sports station in the market, with an all-syndicated lineup. I would rule out any sports format.
EDM? Keep dreaming.
If I were a betting man, the most obvious choice would be country. Now, before you poo-poo it and say that New York is too urban for country to work, keep in mind that country is now very mainstream. It could work, and work very, very well. Most obvious format hole. And very compatible with their other stations.
Second choice would be alternative. WRXP's latest successes have shown that even a decent alt-rock station running on autopilot can get decent ratings. Another format idea that makes sense there.