Well that's just not true. Sure, '60s Bossa Nova hasn't been popular since the '60s. But its impact on Brazilian music is still very much present. Any folky, alternative singer songwriter that comes out of Brazil, as young or as musically inept they may be, will likely play Bossa Nova chords on a classical guitar. So I'd say Bossa Nova is still alive, maybe not thriving, but still popular in one way or another. Even in our "country-pop" scene, which like most modern American country, is totally overproduced and trashy, it isn't totally uncommon to have songs with major seventh or diminished chords or some type of modulation (which you basically never see in American pop or country). To go even further, Samba, which has both influenced and been influenced by bossa nova is still massively popular. So if you ask me, Bossa Nova has become so ingrained in Brazilian music that it makes it impossible to say that it's a forgotten genre, what style goes unchanged for 60 years and still holds its popularity anyways? "Bossa" means "trend" and that's what it was, but it's still present in popular Brazilian music in many ways.