As several others have mentioned, AM is almost dead, and it probably will be gone in most of our lifetimes.
There are certainly select markets where the move to FM talk has really taken off. This will probably never happen in NYC, but in my hometown of Birmingham there are three FM talkers now and one FM sports station. That's four music formats (Hot AC, AAA, AC and Active/Modern Rock) taken off for talk. Other than AAA, those aren't exactly niche formats.
Useless trivia time… These are big signals: a C2, a C1 and two C0's, although two are out of market rimshots. Three of the four have market-heritage calls (WAPI, WERC, WYDE) but only one (WYDE) runs stereo. Three of them run HD (not WAPI). The sports station (WJOX) runs mono with HD and no subchannels which seems like a waste of electricity considering the market's challenging terrain, which renders all HD signals useless.
Birmingham is also a front runner in something that I think will keep the AM dial alive for a wee bit longer, that will have little effect on the NYC dial: AM-to-FM translator pairings. The market has had up to 4 AM simulcasts on FM translators at the same time. So while the market lost four music formats to talk, it gained four music formats on FM (Neo Soul, Active Rock, Rhythmic Oldies, Gospel).