Perhaps it's best to be seventy-ish, but so far as I am concerned, the lyric simply addresses aging. Companions gone, dreams spent, no one left to take care of you and all you'd planned for that now gone.
And by the by - the version I know and has gained such popularity is by Dolores Keane, admittedly now singing an octave or three lower than she used to. She tho, not he.