[js1138]

Even after an organism is established, what has been created before is not necessarily available, because without any context, it is useless. Which is why, perhaps, DNA contains so much junk.

"Junk" is simply stuff currently in disuse. In a changed context it is available for repair and re-use.

[Frumious Bandersnatch]

"Junk" is simply stuff currently in disuse. In a changed context it is available for repair and re-use.

But the point is that it is totally out of context.  in order for it to be useable, the ordering of the DNA helix must be radically altered.  Even then we don't know enough about DNA in general and DNA ordering specifically to know what (if anything) will happen.  All we know is that the more we learn about DNA and RNA, the more complex these supposedly simple building blocks actually are.  To date chance mutations and rearrangements of DNA sequencing seem to be more deleterious than otherwise.  But even of that we cannot be sure.