To me, Dean is completely free of the deal. Should he die now, hell shouldn't be a threat anymore. As I see it, only Castiel can send Dean back there now. Him or any of his fellow-soldiers, I suppose, but it'd be independent from the deal.

Plus, as far as I'm concerned, I consider that the deal was honoured, anyway. Dean was sent to hell as he was supposed to. The guys in hell should have better guards, imho, it's their own fault if God's soldiers can breeze down there and pull souls'out without anyone being the wiser, right? ;-)

So, all isn't lost for T:TSCC, then? Good to know *fingers crossed*