I think some of your suggestions derive from a misunderstanding of the principles at work; or at least as the founders intended them to work.
There is no constitutional mandate, provision or basis for what is spoken of as a "living constitution". This is legal and judicial doublespeak for the political laziness of wanting to get around the only constitutional provisions for amending the constitution - the formal amendment process. The question is not whether or not the people's consensus of what the constitution says and what it means should evolve. The question is how should that evolution be moved from concept, to consensus to law. The only constitutional mandate for reflecting that evolution is the amendment process. It is how we brought in women's suffrage, lowering the voting age and many other "rights" and changes in the last century. Liberals abandoned the process and started using judicial fiat when they could not obtain democratic majorities to provide the democratic basis for constitutional change.
A constitution is not "law", it is the legal foundation for law. It is not intended to be minute, detailed policy and thus a provision of the constitution should not automatically be dispensed with by some arbitrary date, or you undermine all law that has used that provision for its foundation; you leave those laws hanging with no mandate for them in the constitution.
Courts, after any number of years (less and more) do revoke earlier precedents. Such actions should still be held to the clear intent of the constitution, but there is no good reason that they should be more revokable or less, by any number of years.
The idea of life-time appointment of judges went along with, and not contrary to judges ruling on the basis of original intent of the constitution. It is part of the concept of the intent of their independence; the reason for their independence; to hold congress and the executive to the original intent of the constitution, unless and until the democratic processes of the people changes the constitution. Original intent and judicial indpendence were expected to protect and uphold the constitution - not re-write it. The insulation from political influence, and particularly to immediate political influnce was to preserve and protect the intent of the constitution in spite of political opposition at the moment - political opposition that wants the constitution looked at differently but has not produced the national consensus to amend the constitution. It was intended to protect the provisions of the constitution from congress passing a law that violates the constitution, or from the executive ignoring a law passed by congress.
Having abandoned orginal intent, the current Supreme Court simply writes a new constitution, by judicial fiat one ruling at a time. It is not a "living constitution", it is a dead constitution that is replaced with the personal opinions of five out of nine judges.
Thanks for the reasoned and articulate response. Your points are well-taken but, in my opinion, wrong. Your concession that my comments were prompted by considerations of "principles...of how the founders intended them to work" renders much of what followed moot. If the judiciary worked the way the founders intended it to we wouldn't be havng this discussion. My proposals are intended to have consequnces similar to that intended by the founders. Your points are well-stated but have no more practical effect than paying some street crazy to stand in front of the Supreme Court building and shout "Observe original intent!"
As to specific points:
I do not believe in a "living constitution." Perhaps I stated my position badly. My point is that the concept of stare decisis is inconsistent with the concept of a "living constitution." Let's have one or the other. What we have now doesn't make sense.
I did not advocate "dispensing with" any constitutional provisions at an arbitrary date. I proposed limiting the precedential value of Supreme Court decisions to a term certain. This will have one very practical result: Right now, the Supreme Court is rather lethargic about granting certiorari in matters that may have been half-assed decided. If we limit stare decisis, lower courts will gradually reject unsound precedent (and follow well-grounded rulings) so the Supreme Court will repeatedly be re-presented with weak rulings and have a chance to address them.
The life appointment of judges was an iffy proposition from the outset. It likely was the brain-child of the brilliant but self-destructive Hamilton, who wanted the executive to also serve a life term. Franklin wisely observed that the mind sometimes putters out before the body. I am dubious of the notion that executives appoint judges with the expectation that they will "grow" into their office. Life tenure in the extreme is more likely to produce decisions flavored with senility than wisdom.
The Supreme Court bought into that Blackstonian twaddle that courts merely declare what the law is, much like Michelagelo thought that his job was to free a sculpture of the excess stone. Some legal scholars interpreted Blackstone to mean that the only valid Supreme Court decisions were unanimous. Maybe we should only let the Court screw with legislation if the opinions are unanimous.