just out of curiosity, how does that coverage map compare to the map for the current station? The article does say the move is from AM to FM but doesn't inform the reader that the drop in power is not apples to apples.
Orlando powerhouse WDBO AM moved many of their talk shows to 96.5 FM, formerly a great classic rock station with a huge footprint. However, Rush is NOT on 96.5 simply because the better FM signal would have been in direct competition with several AM stations carrying Rush outside of the metro Orlando area (e.g. WMMB in Melbourne).
Rush will do just fine and if the NYT thinks the audience won't follow they haven't got a clue.
FM is a combination of power and tower--you can have lower power but a high tower and get good coverage. Here is the WPHT 1210 coverage map (if you ever want to see a station's coverage go to radio-locator.com and enter in call letters then click View Coverage Map)
AM radio by the way can be affected by such things as having to point the signal away from another station to avoid interference (some FMs are directional too). In Boston AM 1200 has to point the signal from the Newton transmitter due east after dark (as it turns out, toward Boston itself) to avoid other signals on the same frequency. WRKO AM 680 in Boston has to point the signal north and south after dark to avoid stations in Toronto, Baltimore, Binghamton, Raleigh, etc.
Rush should do fine. I did a yahoo search about WPHT dropping him; Daily Kos was ecstatic (and there was at least one site urging WPHT to drop Rush--they got their wish but he'll wind up on a powerful new FM station)
And speaking of power, Rush's new FM station in Fargo is a mere 96,000 watts!