The Holy One makes Jacob a promise so intimate that the Targum cannot bear to phrase it as mere accompaniment. It phrases it as presence.
"I am He who in My Word will go down with thee into Mizraim; I will regard the affliction of thy children, and My Word shall bring thee up from thence, and cause thy children to come up; but Joseph shall lay his hand upon thine eyes" (Genesis 46:4). Targum Pseudo-Jonathan introduces the concept of the Memra — the divine Word — as the traveling presence of God.
The Memra, in Targumic theology, is the Holy One's agent of engagement with the world. Not a separate being, but the verbal extension of the Shechinah. Where the Memra goes, God is present. Where God is present, no place is truly exile. The Targum is telling Jacob that although his body will descend into Egypt, the Divine will descend with him. The long four-hundred-year slavery of his descendants will not be a period of divine absence. It will be a period of divine accompaniment, even if hidden.
Then the promise of return. The same Memra will bring Jacob up — not only in the physical return of his bones to be buried in Canaan (Genesis 50:13), but in the corporate ascent of his children at the Exodus. God is pledging, at Beersheba, both the descent and the yetziat Mitzrayim that will follow.
And the final, tender line. Joseph shall lay his hand upon thine eyes. When Jacob dies — seventeen years later, in Egypt — the son he thought was dead will be the one to close his eyelids at death, according to ancient custom. The reunion will not be a fleeting embrace. It will be long enough to include the death rites.
A father's greatest fear about going into exile is answered: the Divine will travel with him, and the son he mourned will be the one to bury him.