You can't know what a research will bring, maybe it will be discovered that you can do all these tests through some proxy measurement etc. In biology they don't deal with "laws of nature" in the same sense with the physicist, therefore everything is engineering problem since you always have the option to go above or below the biological processes.
You can't transplant a heart until you find a way to do it, you can't change genes until you find a way to do it.
There's no natural law prohibiting measuring something something from the finger that can be measured from somewhere else, it simply cannot be done with the current methods due to some process going on in the human body. The task would be to find a way around the mechanism that is preventing you doing it.