Guests who would not eat
The account begins with hospitality. Messengers came to Ibrahim and greeted him; he brought them a roasted calf without delay (11:69). But when he saw that their hands did not reach for it, he became uneasy and felt apprehension of them (11:70).
The detail is small and very human. He was worried because his guests would not eat — in that culture, refusing food signalled that something was wrong. Children like this part, because it is the kind of thing they notice too.
The messengers reassured him: Fear not. We have been sent to the people of Lut (11:70). So this story and the story of Lut are the same visit, told from two ends.
The news, and the laugh
Then: And his wife was standing, and she laughed. So We gave her good tidings of Ishaq, and after Ishaq, Ya'qub (11:71).
Her reply is recorded without softening: Woe to me! Shall I give birth while I am an old woman, and this, my husband, is an old man? Indeed, this is an amazing thing! (11:72). In Surah adh-Dhariyat she comes forward with a cry, striking her face, and says, An old, barren woman! (51:29).
They answered: Are you amazed at the decree of Allah? (11:73). Not a rebuke exactly — a question. The Quran leaves her astonishment in the text rather than tidying it away, and that is what makes it a real story rather than an announcement.
What became of him
The Quran does not give a long narrative of Ishaq's own life. What it does is place him in a line: Ishaq, and after him Ya'qub, and after Ya'qub the sons whose story becomes Surah Yusuf.
He is named among those given wisdom and knowledge, and among the righteous. In 37:112 he is described as a prophet from among the righteous, and in 38:45-47 he is grouped with Ibrahim and Ya'qub as possessors of strength and vision, chosen and among the outstanding.