Just some responses to offer to some of the comments and questions about sequencing fossil DNA....
Any who have an interest in this topic should absolutely get a copy of Svante Paabo's great book, "Neanderthal Man". It can be tough sledding in places, but the narrative of how DNA was extracted from fossilized remains is exciting and captivating. The question has been asked about why all ancient DNA hasn't been sequenced at this point. If you read the book, you'll be left with the impression that it is miraculous that ANY ancient DNA has EVER successfully been sequenced. DNA is a fragile thing, even when it is modern, fresh and uncontaminated. What you get when you try sequencing DNA this ancient, if you get anything coherent at all, is only bits and pieces of the genome. These DNA fragments need to be stitched together to form anything remotely useful that allows you to identify it as a distinct species. (A time consuming, tedious and expensive process) Even then, you won't have completely sequenced the genome....just enough to give you something useful. Only after doing this will you be able to competently compare the genome sequence to modern descendants' DNA and identify which sequences are likely to have come from those ancestors. Without the ancient template to compare it with, the modern genome doesn't screams, "This is Neanderthal"! Until you have something know to compare it to it is only just one sequence fragment in the modern DNA. You need a map.
I have no doubt that the more refined and consistent the sequencing of ancient DNA becomes, the more likely it will be that we discover modern humans have inherited DNA from far more ancient ancestors than is commonly know or believed. Already we know of one in the Denisovan line, a common ancestor between those people and modern humans, that is so far unidentified. The history of modern and our progenitors is a long, long way from being written, and we are even further away from understanding what we do know. One fossilized bone fragment, if it holds sufficient DNA, could stand what little we do know and the entire predicted model on its head. This stuff is incredibly fascinating, and not just because it might shed light on BF origins as well.