Since when are those decisions immune to future review?
Stare decisis
The 2nd Amendment has been revisited many times and will continue to be so. Previous court decisions are not so sacred that they cannot be overturned. It happens, and a justice noting that it can is not horrifying.
Not to call you a liar by any means, but your statement is simply not true, but it is a good illustration of what stare decisis should do.
The issue in Heller was whether or not there was an individual right. That WAS unsettled law, because the last scouts case was Miller v. US, which came down before WWII. Miller held the 2nd only protected military type weapons appropriate for state militias.
United States v. Miller - Wikipedia, the free encyclopedia
Militas were essentially folded into the state Natl Guard post WWII, with military training and arming being federally regulated (and paid for) to ensure uniformity in case we had another war requiring full mobilization, so Miller was an anachronism. It was also sort of a cop-out on the question of individual ownership as well.
In Heller, a 5-4 decision should put the personal right question to rest. Some on the liberal side (and even those fearing a third Obama justice) think that the Court would reverse itself. It should not. The Heller decision is workable, and it still applies to the facts of how guns are owned in the US.
I think Citizens United is in some danger, because the assumptions Kennedy made about money in politics and people's actions have proven naively mistaken. And Citizens United itself overturned long standing precedent.