I think the conclusion I would draw from the Theranos debacle is "doing hundreds of complex tests from a drop of blood is impossible", not "doing any complex test from a drop of blood is impossible."
That's like asking, "could Enron have been an honest energy company..." sure, with a different board, different executives, different strategy, different technology, different IP, different market sector, and if they sold ice cream cones for fair prices at the local pool.