The translation of this song's name is simply "March 9, 2000". The month and day in this order correspond to "3-9" numerically. In Japanese, one way to pronounce this pairing is "mi-ku". This coincidence has turned the date into a de-facto reference to Hatsune Miku.
As for the year, the song lyrics emphasize the uncertainty of our future. The milestone of reaching the year 2000 no doubt causes one to ponder what's yet to come.
Credit for preview image art: @blazpu_ on Twitter.