According to the definition of a traditional inheritance: we could not have inherited God’s gift of eternal life had Jesus not died. In order for the offspring to receive the gift, the elder generation must die, and therefore pass over the inheritance. If Jesus had suffered the cross, but then before he had died he came down from the cross (or was helped down), he would not have died and passed on the inheritance. Or say that Jesus was not fully God (and fully human), then the inheritance could not have passed from the Father to his children because God did not die (Also, you can not “pass on” something you do not already possess. Therefore, God must have eternal life *). Thus, according to inheritance, Christ’s death must have occurred. It could not have happened any other way.
*- This may be why, in Acts 20:32, Luke uses the word “inheritance” to describe our relationship with Christ. Also, we are “heirs” according to many passages in the Bible to (see also Hebrews 9).