Wow. My memory on Tendulkar was rather different.Sanga I think maintained his output until late and personally I think he is an exception. Tendulkar dropped off a long way from his peak at the end.
His last 5 test seasons Sachin went at (average)
He relied on eye just like everyone else.
Also, I think it is disingenuous to say Smith relies on eye any more than any other player because of his technique. Its unique but I'm not convinced that it is bad and in fact, I actually think it is a wonderful piece of ingenuity. Leverages his strengths beautifully.