Instead of the super-long extended ending...

I would have liked to have seen it included in the films, but I'm not sure what part of the super-long extended ending one would have to excise in order to fit it in. The reunion of the surviving members of the Fellowship at Minas Tirith, the coronation and wedding of Aragorn, the "bow to no man" scene all wrap up a lot of threads. Likewise, the Grey Havens scene is important too.

The only scenes which the Scouring story would have replaced would be the shots of the Hobbits arriving in the Shire and feeling out of place at the local pub. But to do the Scouring properly, Jackson would have had to insert much more material. There would have to be a stop at Isengard so Treebeard could inform them that he had relased Saruman. As the Hobbits approach the Shire, they would have to start getting word that all is not well there. Once they arrive and assess the situation, they'd have to get the entire plan rolling to correct the situation, including the Battle of Bywater and the final confrontation with Sharkey. All told, that would be about another fifteen minutes of film time, I suspect.

The biggest problem is that the average film-goer who's not familiar with the book would be checking their watches about five minutes after the destruction of the Ring, which were already doing so with the ending as presented. I think Jackson made the right call by not including the Scouring - it works as a literary climax to the story arc of the Hobbits, but it wouldn't work as a cinematic climax.