(to be) not long for this world phrase informal
Be likely to die soon.
I am afraid that your grandfather is not long for this world.
By the looks of things, Linda and Peter's marriage is not long for this world.
Your phone is not long for this world. Buy a new one!
To die or pass away
To stop doing one's current activity
1. To pass away
2. To depart suddenly
1. One's success has gone down or ended.
2. One has passed away.