Then Isaac breathed his last and died, and was gathered to his people, an old man of ripe age; and his sons Esau and Jacob buried him. Genesis 35:29 (NASB)
There is a tradition in Jewish writings to pay close attention to the order of names in any kind of pairing or list. The arrangement of names tells its own story or communicates something that isn't always obvious during a cursory read.
Here, at the end of Isaac's life, we see the listing of the twins. We are probably in the habit of referring to them as "Jacob and Esau," but the text lists them as "Esau and Jacob," despite the narrative pointing to Esau representing a tilting towards corruption, whereas Jacob represents a tilting towards the incorruptable. Genesis maitains the Esau-and-Jacob pairing, and this is in alignment with birth order, and not with covenantal preference or righteousness.
This comes right after the mention of Reuben's great sin. Reuben is also a firstborn son, and when you read the list of the sons of Jacob, his place as "firstborn" is plainly written out in verse 23. Despite their sin or tilt towards wickedness and corruption, the position of "firstborn" (and the dignity it carries) isn't lost, even though the blessings that come with it are. In the Esau and Jacob narrative from previous chapters, Esau loses both the birthright and the blessing, and yet he remains in the position of firstborn, highlighted by virtue of the order of the names here.
In fact, the following chapter appears to outline the fulfillment of the firstborn honor by listing out the descendents of Esau.
But there's another tension in the text that we may have forgotten.
So Esau held a grudge against Jacob because of the blessing with which his father had blessed him; and Esau said to himself, “The days of mourning for my father are near; then I will kill my brother Jacob.” Genesis 27:41 (NASB)
Back in Genesis 27, Esau declares that when his father dies and the mourning is complete, he will kill his brother Jacob. There is a threat of violence that seems to hang in the text.
While Genesis doesn't call back to Esau's anger, the next chapter displays the kingdom of Esau that will cause grief for Israel moving forward through the scriptures. In fact, Esau/Edom later becomes a symbolic name for the Roman Empire.