When Young Sheldon debuted, it was merely a way to further capitalize on The Big Bang Theory's popularity. Putting the nerd-centric sitcom's true lead at the center of its storytelling makes sense considering how much Sheldon liked sharing stories from his childhood. In its first few years, the prequel focused on the boy genius, however, that has changed in recent years. As Revord says (via Popternative), Young Sheldon's current primary appeal is no longer its ties to its parent series anymore which is personified by Sheldon. Instead, it's showing the true ups and downs of a family.
The fact that Sheldon has been mostly separated from his family doesn't help his cause. Because most of his arcs take place in East Texas Tech, he feels removed from the bigger storylines in Young Sheldon. For what it's worth, his personal arcs aren't as compelling as his family's. Mandy and Georgie's romance is possibly the best original plot that the prequel has come up with. Missy, on the other hand, is trying to find her own identity in a family where she is often overlooked. All this while George and Mary sort through their marital problems. These stories are more universal than Sheldon's scientific endeavors in college.
After six seasons, it has become clear that Young Sheldon season 7's best path forward is to lean into its familial aspects. Focusing on Sheldon helped in establishing the show, especially while it ran back-to-back with The Big Bang Theory. Much has already happened since then, however. It's much more sustainable for CBS to offer fans a variation of storylines instead of simply being fixated on one character. Since the rest of the Coopers have more realistic stories, it also helps Young Sheldon entice a bigger audience, beyond those who just watched The Big Bang Theory. It may very well be the reason why it can continue after Sheldon leaves.