If He were to set His heart to it and withdraw His Spirit and breath,
The scope of Elihu's discourse to reconcile Job to his afflictions and to pacify his spirit under them. In order to this he had shown, in the foregoing chapter, that God meant him no hurt in afflicting him, but intended it for his spiritual benefit. In this chapter he shows that he did him no wrong in afflicting him, nor punished him more than he deserved.
Commenting on Job 34:10-15
All flesh shall perish together,.... Not one by one, or one after another, as they generally do, but all together; as when the flood swept away the world of the ungodly. "All flesh" signifies all men, and their bodies of flesh particularly, which are weak, frail, and mortal; and if God gathers or takes out the spirit from them, they die immediately, which is meant...
"If He were to set His heart on man," either to injure him, or to take strict account of his sins. The connection supports rather [UMBREIT], "If He had regard to himself (only), and were to gather unto Himself (Psa 104:29) man's spirit, &c. (which he sends forth, Psa 104:30; Ecc 12:7), all flesh must perish together," &c. (Gen 3:19).