So from my understanding of CRISPR, it's fairly impractical to apply gene editing on adults because, unlike children, we have cells in the trillions that need to change oppose to thousands or single digits.
Then how about using a delivery organism that targets mainly stem and/or progenitor cells, while controlling the rate of senescent cells? Won't that eventually replace your old genetic sequence with the new without having to worry about cost & autoimmune problems?