There’s no appreciable drag up there, so if it’s in orbit it’s going to be in orbit for a while, regardless of how big or small it is. Is the amount of energy lost to ripping the debris apart enough to eventually de-orbit the object? I honestly don’t know. My immediate thought is no, barring outside factors, because if it did spacecraft would be torn apart during their de-orbit burns; but I honestly can’t get my brain around that well enough to be certain (maybe the longer time a spacecraft takes de-orbiting reduces the stresses that a piece of space junk suffers instantly).

The kind of crazy thing is that, if a 1,000kg satellite orbiting at an altitude of 36km and a speed of 11,000kph breaks into a thousand pieces, each of those 1kg pieces are still traveling at an altitude of 36km and a speed of 11,000kph.