In what context does the expression "death of a salesman" (81) occur in the play?

Willy is describing his idea of the ultimate salesman. The salesman's name was Dave Singleman. Like the name "Willy Loman," "Dave Singleman" is not just a man's name. Although salesmen, as Willy will later be told by his son, Biff, are a "dime a dozen," Willy believes great salesmen can all be like Dave. But what Willy doesn't see is that Dave is a Singleman, a single man; there are really no other salesman like him. The implication is that to aspire to be like Dave, to dream that he could one day be like this lone master saleman, is futile. Here's Willy, talking to Howard, the son of Willy's first boss:

WILLY: Oh, yeah, my father lived many years in Alaska. He wasan adventurous man. We’ve got quite a little streak of selfreliance in our family. I thought I’d go out with my older brother and try to locate him, and maybe settle in the North with the old man. And I was almost decided to go, when I met a salesman in the Parker House. His name was Dave Singleman. And he was eighty-four years old, and he’d drummed merchandise in thirty-one states. And old Dave, he’d go up to hisroom, y’understand, put on his green velvet slippers — I’ll never forget — and pick up his phone and call the buyers, and without ever leaving his room, at the age of eighty-four, he made his living. And when I saw that, I realized that selling was the greatest career a man could want. ‘Cause what could be more satisfying than to be able to go, at the age of eighty-four, into twenty or thirty different cities, and pick up a phone, and be remembered and loved and helped by so many different people? Do you know? When he died — and by the way he died the death of a salesman, in his green velvet slippers in the smoker of the New York, New Haven and Hartford, going into Boston — when he died, hundreds of salesmen and buyers were at his funeral. Things were sad on a lotta trains for months after that. (He stands up. Howard has not looked at him.) In those days there was personality in it, Howard. There was respect, and comradeship, and gratitude in it. Today, it’s all cut and dried, and there’s no chance for bringing friendship to bear — or personality. You see what I mean? They don’t know me any more.

Ironically, Willy also dies in a means of transportation, but it is not while riding leisurely in a train with his slippers on... no, it is in his own car with his well-worn shoes pressing down hard on the gas pedal.