A family member went on holiday early today. They and their partner have two small DC (the eldest is seven), so they still put a tree etc up in mid December. They will take it down on their return next week.
Of course people have many reasons to take their trees down before twelfth night, but imo the trend for taking Christmas decorations down increasingly early goes hand in hand with the trend to put them up in November! Those that do are often - understandably - bored with them by then.
As a child in the 1970s, my parents didn't put the tree up till Christmas Eve, taking everything down on twelfth night, which was the same as many of their family/friends. By the 1980s they had started putting it up about a week before Christmas, a tradition we've stuck with.