Given the complexity of DNA I think it is near obvious life did not originate on earth. If you assume it did not originate on earth that gives you at least another 10 billion years to work with.
But really there's nothing yet that even remotely necessitates an extra-terrestrial origin for life. The problem is that, each time there was a "winner" in the very earliest more-chemistry-than-life arms-races, it essentially obliterated all record of what the competition looked like. It's not until pretty late in the game that no one new strategy obliterated all its peers - at that point we got the biological domains (prokaryotes and eukaryotes (which subsumed other prokaryotes as mitochondria and chloroplasts)) and viruses. From then on, the arms-races have been at higher levels of abstraction and the fight over the basics of biochemistry is 'settled'.