You know what as long as valve cranks out more games like HL2, TF2, Portals they can do what ever they want. Whats so great about the source engine is its scalability and its ability to still look very good on lower end machines. Valve is smart and they know right now Direct X 10 is just really marketing. Like someone else mentioned Direct X 9 still has plenty of legs left, and for businesses out their they will contiune to develop for the DX 9 because everyone has at least a DX 9 compliant card.