"It is the first time the Supreme Court has unequivocally taken this position on the second amendment." That wouldn't be consider a shift in policy?
Your position and statement implies there was no dissent. The vote was a narrow 5-4. Further, there were TWO opinions of dissent, both signed by all four in dissent.
The court has actually declined to hear most 2nd Amendment cases. So, it seems it would be hard to determine there was a shift, since up until now, they weren't hearing the cases, so there's not much way to determine what their policy was, other than not to hear the cases to begin with.