The fact that he's wearing it at all stuns me. It needs to be maintained by a coven of the greatest wizards around.

Imagine: Harry dies (heart attack, stroke, stabbed by Goyle, whatever) Handless amnesiac Voldemort appears, dies of human transfiguration sickness after a few deeply confused minutes Horcrux network activates.
Best case, this amnesiac being can't figure out how to possess anyone. Medium case, somebody gets possessed by the clueless shade.
Worst case: network was built to supplement current memories with dump of previous ones (we can see by the part where Voldemort Confounds himself before the Mirror that he had thought about the concept of changing his mental state), and the Dark Lord is back in business