In Jessica Radloff's book, The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series, Holland and Molaro discuss considering another parting sequence for the sitcom. As it turned out, co-creator Chuck Lorre had always wanted it to involve the elevator getting fixed, but as season 12 went on, they decided against it.
"Steve Molaro: Chuck always thought the elevator finally opening should maybe be the final scene, but as we got closer, I think you could feel people expecting it. We wanted to do it, but we wanted to try and catch people off guard.
Steve Holland: There was one version of it where they were all walking up the stairs after having gotten back from the airport and their trip to Stockholm, and just as they got to the fourth floor, the elevator would ding and it would open. There was a talk about a moment in which Sheldon and Amy say, "It's crazy; we won the Nobel Prize and in some ways, everything's exactly the same," and then the elevator opens, and that would have been the end of the show. The tag still would have still been them sitting on the couch, but as we were breaking the story, we thought about two things: the moment where Sheldon was freaking out because Amy had gotten the haircut; and the Nobel Prize, it was like the straw that broke the camel's back. So it seemed right for the elevator to open then, and also, I just thought it would be much less expected to have it happen so much earlier in the episode."
After their trip to Stockholm for Sheldon and Amy's Nobel Prize acceptance ceremony, the gang came back home to Apartment 4A for their usual dinner, indicating that The Big Bang Theory may be ending, but their friendship continues. It isn't some kind of end-of-an-era moment like Friends and many other sitcoms did which makes it unique.
For what it's worth, the elevator getting fixed would have also been a great way to end The Big Bang Theory. Suffice it to say, CBS went with the best option by ending the show with the group shot of everyone.
