I Just Thought Of A Depressing Marauder’s Theory.

So we all know that the Marauder’s map is all-knowing, right? However… I feel that it slowly started losing it‘s power as the marauder’s died off. After James Potter’s death… no one ever really talks about the map until Harry’s 3rd year at Hogwarts… when he meets the other 3 marauders. When Sirius dies, Harry suddenly has less of a use for the map until he gets suspicious of Malfoy. However… I came across a depressing theory. What if… after all 4 marauder’s had died… the map stopped working. The only thing keeping it going was Remus Lupin. After that, all it said was “Mischief Managed.”