Breathing Digital - Is Second Screen a fad or the growing slope of a demographic mountain?

I was having that familiar discussion in London last week about what 2nd screen was and whether or not this was a real market trend or just an overhyped fad.  Of course, it is always hard to know these things before they happen (else we would all be very rich), but in thinking through a new way to answer beyond stating the most recent statistics of 80%+ people using a 2nd screen while watching TV only to hear the the person I am speaking to me immediately tell me they never do, etc, I thought about a key note I saw at a conference in 1999.