Yes, the use of direct-to-consumer DNA databases, and their derivatives, such as GEDmatch, by police agencies will kill off DNA testing. That's too bad for me, because even after three years of almost daily use of genetic genealogy to try to find my biological family, I have not had the "magic" close match needed to be able to do so. Now, I see the beginning of the end.
Just today, CBS News had a story about a cold case being solved, and the story prominently mentioned GEDmatch. Anybody I might ask at Ancestry.com to upload there will probably see that in a Google search, and figure that I might just be a cop, looking to collar one of their relatives.
The only way to get the toothpaste back into the tube is for a Supreme Court decision stating that the fraudulent use of consumer DNA databases is an unreasonable search and seizure within the meaning of the Fourth Amendment.