In our quest to replace all useless organic parts of our body with upgraded synthetics, we have come across a key ingredient: Oxycyte. Oxycyte is a new artificial blood that can absorb 50 times the oxygen of normal blood. Sure, synthetics still aren't good for organs in the long term, but we'll be getting those pesky space holders removed soon enough. We need more room for the laser canon.
Actually, Oxycyte is a derivative of non-hemoglobin synthetics that have been around for some time. It's currently being tested as a substitute for donated blood during emergency surgeries where brain injury from a lack of oxygen is common.