Example: for a decade now it's been possible to take a standard blood draw from a stage 4 cancer patient, sequence all DNA circulating in the plasma, distinguish the cancer DNA from non-cancer, and use the cancer sequences to inform treatment. In 2022, this is readily available to most stage 4 American cancer patients.
The obvious logical future extension of this, is draw blood from any person, and see if they have any stage of cancer. This is something that is being actively worked on, and is currently in the experimental/cutting edge state; expect to see it become somewhat common/affordable in perhaps another 4 years.
Theranos claimed to be able to do the above, a decade ago, and with an order of magnitude less biological input material than current technology requires. One reason they garnered so much attention, is that people generally familiar with the field knew that much of what they claimed, were things that were possible but were 15-30 years out based on the trajectory of technology at the time. So it was plausible that a genuine breakthrough had occurred that massively accelerated that timeline.
Sadly, as we all now know, that was not the case.