...Like John Hamm said at the Emmys, "It's cable" (not network)
Thank God for that, because the show never would have been allowed to run on network as it has on AMC.
Very little in Mad Men is thrown-in for no reason. I think that elderly couple in the hallway at the end of Ep 404 (The Rejected) is there to show a couple of things.
Don is torn between his (The Greatest) generation and the next one, which is occupied by angry, anti-establishment pop-art beatniks. Within his own place in time, he was a misty shadow of a person named Don or Dick, and doesn't really exist within it. His laments his own self-imposed disenfranchisement throughout the series. In Ep. 407 (The Suitcase), he tells Peggy that, "...The only person who really knew me is dead."
The next generation hates commercialism and advertising along with it, so Don has no place there at all, yet there he resides. Peggy is straddling that line as well, though I think she can make a go of it.
As Don watches the older couple, he sees how he doesn't fit in...anywhere. His imagined idyllic life would combine carefree bachelorhood with all the trappings of family, but he cannot have both. The worst part is that he finally had a real family, but he is so averse to this lifestyle that he destroys it. He had Grace Kelly waiting for him in the perfect colonial revival in the suburbs, two kids and the job he'd always wanted. But it wasn't enough. Somehow this old couple persevered, but he could not.
The old couple knows how to keep their dirty laundry where it belongs - hidden deep away from prying eyes and outside judgement.
Don wants to live this clandestine life, but nothing is sacred and nothing is secret for him anymore. His every move is scrutinized in the smaller SCDP offices - and he's taking his medicine. Roger Sterling knew about Betty's affair long before he did, his secretary effectively broadcast their tryst throughout the office and Joan gave him Ms. Blankenship as an answer to his philandering. Professionally, even though he's got his Clio, there are big holes showing in his game.
I don't think anything in this show is about pears and that's why I love it.