Oh, I don't agree that George's life would die. I think he and Fred seemed to be grounded enough young men that though they were goofy and fun loving, knew EXACTLY what they were facing, and what could happen. I think George would miss him terribly, but would go on living his life in honor of his brother.
I read an interview with Rowling where she says that George goes back to the joke shop, gets married and names his first son Fred.
She did mention George in an interview after the book release. Ron comes to help him keep the joke shop open. George marries and names the first son Fred. (She also mentions that Ron becomes an auror, so it is a bit confusing.)
Oh, yes, he would live his life and still be funny and grounded, but he would be twinless and people who lose twins never really get over it.
I had a taste of that kind of loss when I lost my beloved sister who was also my best friend. There’s always a big empty space.