In Prague, just to give you an example I know well, the number of apartments for short term rent is pretty high and it grew pretty quickly too in the 90's.
The reason was not Silicon Valley growth but the end of socialism.
Internet was not involved but I don't really think the source of bookings or change really matters.
What matters is the effect on the rest of the economy and society.
As you say some people (owners in this case) profit in this situation while others suffer and are pushed in less desirable areas (that would be 99% of the time out of the center in Europe, and out of nice neighborhoods in US).
At the end for "people" aggregate (vs corporations) it may be a neutral change.
What I am saying is that NY may seems pretty special but it may not be.
The fact that Hotels are so expensive may be a sign that Airbnb is bringing some needed change in an overly protected business environment.
What if Airbnb forces some hotels to close and they free up residential space? Is this a possible effect?
It's possible, but highly unlikely imho. I haven't found AirBNB prices in NY to be all that appealing (I live in NYC). They are at a discount, but not a great enough discount for me to go AirBNB over the comfort and convenience of a hotel and often find great hotel prices with apps like HotelTonight. And when I've looked elsewhere, AirBNB places are similarly underwhelming. I can see it being cheaper for a group to rent a nice apartment vs several hotel rooms, but I often travel alone and find comfort in the convenience of a hotel.
What I am saying is that NY may seems pretty special but it may not be. The fact that Hotels are so expensive may be a sign that Airbnb is bringing some needed change in an overly protected business environment.
What if Airbnb forces some hotels to close and they free up residential space? Is this a possible effect?