How Is Folk/pop Music Considered Rock

Will current day pop music ever be considered 'classical'?

I don’t think that very much modern-day pop music will become “classical music”—as others have said, there’s usually a distinction made in calling something classical music: that it be intended as ART MUSIC, rather than popular music. That said, there are three ways that pop music tends to transcend this distinction that I think are being overlooked in the other answers.First, there’s a tradition of “pop music” being retroactively reinterpreted as classical music for convenience. The opera world is a great example of this. Basically the only place you see Gilbert and Sullivan is in opera houses, but also things like Show Boat are being done as much or more in opera houses (with opera singers) than as musicals, and I’ve seen everything from Cole Porter to Sondheim done in (artistically significant) opera houses in the past year. Then there are things like Yeethoven (see below) that mashup classical music with pop music, the ways that pops concerts have transcended pop music, etc. It’s clear that with enough time, the most artistically special pieces of pop music get appropriated as classical music.Second, there’s a (less extensive but very real) tradition of classical music being written for pop venues. I’m thinking, again in the opera world, of something like the operas of Gian Carlo Menotti. These were clearly classical operas, but he wanted them to be performed on Broadway, in English, because he wanted the pop culture element to be included in the work. Now they are only performed in classical venues.Third, there’s a ton of pop music influence in music written in classical idioms. This should be clear for everything from Rhapsody in Blue to Darius Milhaud’s La Creation du Monde (see below) to Shostakovich’s works for Jazz Orchestra: these pieces were written with an awareness of the emerging cultural force that jazz was and would become. Where do you put them now? Classical homages to pop music? Feels easier to consider them genre-busters, as far as I’m concerned.So there’s some fluidity between these forms—it’s definitely not a simple distinction, and I agree with the premise of the question that the aging of pop music allows for quite a bit of flexibility.

Why is acoustic driven Americana folk rock music so popular today?

Some listeners are old. Beatlemania happened fifty years ago, so let's not pretend that the old generation gap rifts are still so glaring. Older rockist listeners are not interested in Lawrence Welk, but they aren't into bubonic plague metal or Kendrick Lamar either. Americana fits them well.Among younger listeners I see it as a cyclical fashion thing. Decades ago there was a kind of path from beatniky stuff like the folk revival to Dylan to Simon and Garfunkel and the Beatles at their more sensitive and literate. That stuff was more collegiate and cultured than Elvis, who actually was Southern and into Dean Martin and considered crude. The banjos and hootenanny vibe of a lot of current music is basically a revival of an older slightly intellectualized fashion.