I just thought the same thing and wrote about it on today's spoiler thread. It's worth a try but a move like this would be very obvious, especially since all the GC riders will be keen not to let gaps open up in case they lose a few soft seconds from a slack moment.
But it probably represents Armstrong's last chance for yellow - unless he's got his Ferrari legs - so you'd imagine he gives it a go.
little kick off the front in the last few 100meters perhaps...no?
good pr and realistically could be his only chance