The mid 90s were special. You could buy a 600 sqft co-op alcove studio for the same price as a similar apartment in Tel-Aviv, but rents after expenses were over 3x higher than in Tel-Aviv. Today purchase prices are again similar, but the net rent ratio has gone down to about 1:1.5, which is surprisingly low given the income gaps. There are some factors not measured such as the large number of properties being systematically rented out as hotel rooms via airbnb (12,000 apartments listed + many rooms) and such, the fact that independently wealthy peeps are increasingly buying property and taking it off the market for all eternity, etc. but those hold true for every high-quality major city.

So I'd say they're right prices are a little high now (I think by about 30%, which is better than their worst case but obviously substantial) and that they were very low in the 90s, but given that high prices have survived the crisis, it could be a very long time before we see an adjustment...

Of course there are some additional and mostly negative factors involve finding tenants with the ability to pay, the tax-abatement cliff, uncertainty about the value of the nyc brand (seems very strong, but who knows), etc. All in all, there are better real estate investments to make than nyc resi at the current levels.