Jesus is able to save us forever (“to the uttermost”) and that he intercedes for us forever (“he always lives to make intercession for [us]”). These two things are directly connected. Jesus is able to save us forever “SINCE (because) he always lives to make intercession for [us].” In other words, our future salvation rests on Christ's continual intercession for us. Those of us who HAVE BEEN saved are also BEING saved by the continual intercession of Jesus in heaven.