I finished the Romans 6 section of the devotional I'm writing on Romans 1-8, to go with Paul: Soldier of Peace, which is scheduled to come out in July. I was reflecting on the well known verse, Romans 6:23: "The wages of sin is death, but the gift of God is eternal life through Christ Jesus our Lord."
Although Paul here primarily has in mind the time prior to being baptizing into Christ, dying with Christ, dying to law, it struck me that the context might easily push us to see this comment also in relation to the believer. When the Romans used to be slaves to sin, they used to surrender the parts of their bodies as instruments of Sin. "The end of those things is death" (6:21).
These are the things Paul is telling them believers cannot continue to do after dying with Christ. "Should we sin because we are not under law but under grace? By no means!" (6:15). The climax of the chapter is then the last verse. The wages of sin is death. The end of these actions is death. Don't do them.
On balance, the trajectory of the chapter pushes us to conclude that the wages of sin could become death for a believer as well.