Not saying that will be the case in every instance, but I do remember the actual video that got BOTH my sons into music was an "AC/DC Live In Germany" video that I put on TV when they were both toddlers. They were duck walking all over the house and begging me to put the DVD on over and over again until I (who am a huge Angus Young fan) was thoroughly sick of it. Many years later, I took them to an AC/DC live concert in Sydney, during their "Black Ice" tour.
Exposing kids to such raw energy and musicianship on a semi regular basis is critical IMO. What they don't see, they cannot be inspired by. I also know that they won't always be inspired by what I like, and that is fine. Both my sons went through a 'thrash metal' phase, which wasn't my favourite, but it still formed a large part of their musical journey.
I learned in the mid 90s, probably inspired by Oasis, and related Britpop artists. Of course very quickly I was listening to older musicians like Page, Hendrix, and Clapton. Even then though my friends who played music and I were well aware that the age of guitar hero was over and that it was quirkier to want to play guitar music than it had been ten years before. There were no more Slashes on the horizon.
Music scenes seem likely to never be so one dimensional as they were in previous decades, because there's something for everyone online, and I can't see a time when Top of the Pops has three big rock bands playing on the same night ever again.
Emphasis on a bunch of kids. As someone who likes guitar it pains me to say that this seems true.
My son is 11, in a (very) music-heavy school. When I was his age I think almost every boy (and some girls) in my class learnt guitar - it was the instrument.
In my son's class I think there are 2 learning it.
The guitar will never die, but the popularity isn't what it was.