I always thought "scar" as the last word meant Harry died!
My idea behind it is a bit loose, but basically, if the last chapter told the future of the characters, I thought that it would end with Ron and Hermione telling their kids the story of the "Boy-Who-Lived" and go something like (please excuse my poor example of dialogue) this:
"Harry was the only person to ever have survived the the killing curse. He was not entirely unharmed, however. Voldemort's failed Aveda Kedavra left Harry with a special scar..."
With the ellipses signifying the beginning of the Harry Potter story; i.e. got the scar, went to live with the Dursleys, found out he was a wizard, hijinks at Hogwarts, defeated the dark lord, etc. Basically, it would be a lead in to the whole series.
I do realize this is not JKR's style and might in fact be too meta and post-modern for the series. This scenario immediately popped into my head when I heard the last work was going to be "scar."
LOL! My "imagined" closing goes something like this:
Three months later, Harry walked through the doors of Hogwarts and entered the Great Hall. As he walked between the tables, he noticed the students whispering and pointing at him. He smiled to himself. "At least
that hasn't changed much" he thought.
There had been many changes in Harry's life recently, some good, and some bad. Professor Snape's death had affected him more than he could have imagined, and he still felt guilty that Snape had given his life to help Harry. (However, he didn't feel the slightest bit sad over the demise of Delores Umbridge.) Draco Malfoy was still in St. Mungo's, and although he would never fly on a broom again, he was expected to otherwise fully recover. However, the same could not be said for Pansy Parkinson - the large pig's snout was not able to be removed, and the last Harry had heard was that she had been seen rooting for truffles in the Forbidden Forest. Sightings of her were frequently discussed on the front page of the Quibbler, where Luna, as Assistant Editor, made sure that "Pig-Nosed Pansy" replaced the Loch Ness Monster as the most sought-after photo in the UK.
On a happier note, though, Harry was finally free to leave the Dursley's, and had found a small cottage in Hogsmeade that was just right for him. He had given the house on Grimmauld Place to Tonks and Lupin as an engagement gift - there were too many memories of Sirius in that house for Harry to ever live there. Luckily, Fred and George were able to dislodge the portrait of Mrs. Black using one of their patented Hag & Harpy Hammers.
Harry had proudly stood as best man at Ron and Hermioine's wedding over the summer. It was a lovely ceremony, but their honeymoon holiday was brief. Since making the Chudley Cannon Quiddich team, Ron was on a brutal practice schedule (even second-string players had to attend all practices). Hermione was just as busy - thanks to Dobby's heroic actions in the fight against the Death Eaters, thousands of wizards now belonged to S.P.E.W., which was quickly becoming the most popular civil rights foundation in England.
Harry himself planned on proposing to Ginny after the school year was over, and hopefully she would accept. If she did, he would become an "official" member of the recently-reunited Weasley clan. Having Percy for a brother-in-law wouldn't be so bad now that he had redeemed himself. Percy had even felt so guilty at not attending Fleur and Bill's wedding last year that he performed a tricky little charm that inserted a smiling, waving Percy right next to the bride in the wedding portrait (much to Fleur's chagrin).
One of the biggest changes in Harry's life was that, for the first time, Harry was entering Hogwarts not as a student, but as a teacher. Becoming an Auror had seemed so important to him when Voldemort was alive, but now...well...now he felt that teaching young wizards was what suited him best. After all, who better to teach Defense Against the Dark Arts than the "Boy Who Lived?"
The Boy Who Lived was now the Man Who Lived. As he took his place at the teacher's table, he grinned at Hagrid, who was sitting on his right, and Neville, the new Herbology teacher, who was sitting on his left. Headmaster McGonagall gave him a brisk nod and a quick smile. As he looked out over the sea of eager young faces, he unconsciously rubbed his forehead. But...there was not a single bit of pain from his scar.