It can be argued that a decade's musical identity (https://www.reddit.com/r/NoStupidQuestions/comments/3bpjc3/why_do_the_90s_80s_70s_etc_all_have_a_distinct/) is formed like 1-2 years after their start. But on the contrary, are there any songs that might have defined the next decade before it officially started? Songs that were you could say, previews or harbingers of things to come musically for the forthcoming decade. For example, "Video Killed the Radio Star" (https://en.wikipedia.org/wiki/Video_Killed_the_Radio_Star) by The Buggles (which is famously, the first ever music video to ever be played on MTV when it debuted on August 1, 1981) was actually originally released in 1979. But the song sounded "very '80s" with the synth sounds (https://tv.apple.com/us/movie/the-synth-years-video-killed-the-radio-star/umc.cmc.7bj0a0o4ml8x24iao99o61ni5).