So Baltasar Carlos died at the age of 16, forcing his father, Philip IV, to remarry. This remarriage produced Carlos II, the last of the Spanish Habsburgs. So what if he didn't die? Would the Spanish House of Habsburg continue or would this just prolong the inevitable? How would Spanish domestic and foreign policy change with a competent monarch at the helm? Who would he marry? A French princess, an Austrian archduchess or someone else?