One of the things I have noticed is that most of the retail outlets that where in business back in the 50s, 60s, 70s and even 80s are no longer advertising in model railroader. Charles Ro, AHM, IHC, Mitchalls, Ted Engine House, Standard Hobby, etc. etc... The only one that I still see is Trainworld/Trainland, which is still in business. I don't believe that the internet put these companies out of business, as any business man with a pulse would recognize a new-great-opportunity for increasing sales, like the internet.
Businesses come and businesses go, without doubt. Some have longevity, some don't. However, for all these retailers to be gone is an interesting thing to think about!