They already have, and on more than one occasion.
Yes they have indirectly but never directly on the nbC term in a presidential eligibility challenge. As Justice Thomas said, they are “evading” that issue. I believe Chief Justice Roberts has been the prime-mover behind “evading” addressing nbC in a presidential eligibility challenge since Obama came on the scene, since the already knew the answer would not be in favor of Obama’s status and were afraid to address it at the time out of fear of the “racism” charge, or someone had some dirt on Chief Justice Roberts that kept him from encouraging the court to take up an eligibility case back in 2008 and 2009. Now he is backed in the corner and in CYA mode as more and more ineligible candidates have come on the scene, like Harris.
For some relevant SCOTUS cases on kinds of citizenship see Section 4 at this link: https://www.art2superpac.com/issues.html
Also see this chart for the various kinds of citizenship mentioned in the U.S. Constitution: http://www.kerchner.com/images/protectourliberty/Citizenship-Terms-In-Constitution-Chart.jpg
It’s been discussed but not on all fours/on point such that POTUS candidates can clearly and inarguably be winnowed down at the Secretary of State level (as in, the SOSs of the several states, establishing the contents of national election ballots) to plain vanilla U.S. Americans only.