Those two backs, and Howell at QB, make them very dangerous. I think some ND fans don't realize how explosive they are capable of being.
I think ND's D has been really good this season, with a couple of caveats: pass rush and consistency in CB coverage. So I both agree and disagree with you on the ND D. I think some fans put too much weight on passing yards surrendered, such as in the Clemson game. But ND has shown vulnerabilities that a great offense like UNC could exploit. ND struggles to rush the passer, and CB coverage isn't always strong. It isn't a complete D . . . yet. And I do have some worries about UNC and potentially a rematch with Clemson. I'll go out on a limb, though, that if ND holds UNC under or close to 100 yards rushing, ND will win comfortably -- even if Howell throws for 350+. If Williams and Carter are effective on the ground, ND will have to score a lot and outscore them . . . and unlike some fans, I do worry about the loss of two starting OLs. ND might not be able to afford a quarter-plus of "adjusting" to the new line configuration.
Wanted to note also that Javonte Williams was the kind of recruit that a lot of ND fans would have complained about. He was a low-3* with little recruiting fanfare (ranked as the #1476th player nationally by 247.) Carter was also a 3* recruit, though a little higher up the charts.