Just the company I am with has 5, and there are already about 50 on the air
and another roughly 200 ordered and in construction.

Don't make the mistake of equating the number of stations which have
ordered or installed IBOC equipment with the number of stations which
are actually _using_ IBOC. AM stations which have abandoned use of
IBOC (even if they may still have the equipment installed) include
WLW, WKDL, WSB, WWDB, KIXI, WPAT, WWJ, KABL, WZRC, and WTOP. As of
March, the grand total number of AM stations actually transmitting an
IBOC signal was around 20. Perhaps there are a few more today, but I
haven't heard of AM IBOC use growing by leaps and bounds in the past
few months.

Also, KNX, WMTR, WWTR, and WCTC may have filed a Digital Notification
with the FCC, but as of yet, none of these are actually transmitting
IBOC -- in fact, WCTC is still proudly broadcasting in AM Stereo, and
in a recent conversation with their Program Director in which I
discussed AM Stereo, he did not mention IBOC at all. I think Greater
Media has notified ALL of their stations (AM and FM) as IBOC with the
FCC, regardless if each station has any plans to actually install and
use it or not.

The two NY stations have horrible DA systems, neither being optimized for
low-Q and bandwidth.

Excuses, excuses. MOST stations in the country are "sub-optimal" and
are likely to have many of these same flaws which will seriously
inhibit their success with IBOC, or even make it impossible. (Even
WOR says "our upper sideband does not exist north of Paramus, NJ" --
how's that for a lousy DA?) So if/when IBOC is mandated, what will
happen to these stations? Rather than spend $100,000+ on a complete
overhaul, I bet many would just go off the air -- which is both good
and bad. Good, because it would finally "clean up" the AM band and
restore useable nighttime coverage area on Class B and C signals.
Bad, because just as many "good" stations (in terms of programming,
ratings, and listenership) will be forced off the air as "bad"
stations, and those that are left will be forced to use IBOC -- even
though the "de-cluttering" of the band would once again make hi-fi
analog AM a reality.