I have always been interested in the facts of alum fatigue in bike parts . . . I suspect most of this is overstated.
to the OP - there is no frame that will 100% last the rest of your life and such a demand is unrealistic. A crash or heavy abuse can bring any frame to its end. I think steel gives you a great shot at having a frame that lasts that long, but luck is going to be required as well.