Similar to the first amendment where the USSC said that free speech protects nude dancing, all 50 states must abide by that ruling.
Do you want 5 USSC justices ruling that "arms" in the second amendment does not include handguns? (not far fetched -- the 7th Circuit said exactly that in Quilici v. Village of Morton Grove -- "Under the controlling authority of Miller we conclude that the right to keep and bear handguns is not guaranteed by the second amendment"). That ruling would then apply to all states.
Do you want 5 USSC justices ruling that "bear arms" in the second amendment does not include concealed carry? (again not far fetched -- the Rhode Island Supreme Court said in State v. Storms, 1973:
"... "the prevailing view" was that "a constitutional guarantee to keep and bear arms is not infringed upon by legislation which, in broad terms, forbids the unlicensed carrying of a pistol or revolver upon one's person excepting only in his home and place of business or upon his land."
"Superior Court Judge Michael A. Silverstein concluded that based on the Storms case and the state Constitution, he was "unable to declare that a person in Rhode Island has a fundamental right to carry a weapon outside the limits of his or her own land or business with or without a license which, in turn, would entitle them to due-process protection when applying for a license.")
Now, these kind of decisions at a local or a state level are one thing. At the federal level, with the decision affecting all 50 states -- why would you want this??
Why do you think the USSC will protect your gun rights? Why do you assume this?
So how would such a ruling adversely affect the RKBA?
Do you want 5 USSC justices ruling that "arms" in the second amendment does not include handguns? (not far fetched -- the 7th Circuit said exactly that in Quilici v. Village of Morton Grove -- "Under the controlling authority of Miller we conclude that the right to keep and bear handguns is not guaranteed by the second amendment"). That ruling would then apply to all states.
States with the RKBA would still have it.
How would such a USSC decision make the RKBA less secure?