Folks on the New York Radio Message Board are speculating about his replacement. There were two specific people mentioned who already work for CBS New York.
Rick Gillette is currently programming 92.3 Now, and previous programmed both a Rhythmic CHR and a Classic Hits station (KOOL-FM) in Phoenix. He did really good things for KOOL, revitalizing it much like Thomas did CBS-FM, so he's a definitely a worthy candidate. Plus, it would give him job security if 92.3 flips to WFAN-FM.
On the other hand, Lenny has been with CBS-FM as APD/MD for a while and knows the station, plus he's had PD experience at Sirius/XM and stations like WDHA. So he'd be perfectly qualified as well. But I think if he stayed in the APD/MD position, and Gillette became PD, they'd make a great team.
Of course, they may decide to go outside the box and hire someone from elsewhere, but they do have two perfectly good candidates right here.