The Affair Season 5 Episode 4 pulled back the curtain to reveal that Joanie's narrative is taking place sometime after 2050 and that Cole is dead.
Joanie is struggling to exist in a world without her parents, and that's very evident based off the way she's been acting throughout the handful of scenes she's been a part of to date.
What happened to Cole following the death of Alison is still very much unclear.
He survived over three decades later, but given that his home was still filled with photos of Alison before his death, it's likely that he never got over her death.
The death of Alison affected him more than it did Noah, so there's no telling what became of him.
Joanie ridding the house of Gabriel's toy box