In your opinion. Doesn't make it so.

So in your opinion Bruce finds peace, becomes immortal and lives forever? No. He's still gonna die. Either in the cowl or on a beach somewhere.
What Alfred did serve, which certainly wouldn't have had to be changed, is a counterpoint to John Blake and others who didn't feel that a man in Bruce's position was doing enough. Quitting for 8 years and letting orphanages lose their funding were BAD choices. Giving his life would have made up for those much more than donating a mansion that no longer meant anything to him.
Alfred is like the wife who cries that the hero (whether super, police, fireman, whatever) shouldn't go out and risk his life but the hero does it anyway because he believes it's the right thing to do. Having a close person upset and begging to have the hero get out of the line of fire doesn't demand that the hero retire in order to have a satisfying arc.