Let me first say that the theory of Evolution has very little to do with the origins of life, and much more to do with what happened after that. Like all scientific theories, it became a theory (instead of a hypothesis) by having the evidence to back it. Hypotheses are thrown out all the time, because they’re just untested or minimally tested ideas that sometimes are rubbish. Once a hypothesis becomes a theory, it is fairly solid, with much supporting evidence. Of course it is possible that this theory could be unproven, I guess, but with the full massive weight of information and support holding it up, it would be very unlikely. Impossible? No – the right evidence could even disprove the theories of Gravity, Relativity, and Thermodynamics.