There are any number of ways the theory could be falsified. Another mechanism of genetic change could be discovered that was somehow not subject to natural selection. A genomic analysis that didn't conform to the nested hierarchies of phylogenetic analysis previously discovered would also falsify common descent.
Or, one could find biological systems that couldn't have evolved because because they are irreducibly complex...oh wait, if someone did that, they would just be accused of arguing from ignorance or worshipping the God of the gaps. That's what was said when Behe presented examples. IDers could find 100 ironclad examples of irreducible complexity that stood up for 100 years and they would still not be considered falsification of evolution. They would be considered "God of the gap" claptrap no matter how strong the science was.
The reality is that evolution will never be falsified, because any work that appears to falsify it will be judged unscientific. It will be said that those who made the discovery are arguing from ignorance, and evolutionists will say, "No, you must be wrong, we proved in in the lab." They will also accuse said scientists of being closet creationists if they either have any admitted faith or anybody at any creationist organization has ever said the work could be useful for promoting the creationist cause.
For too many, science has become Professor Love's Traveling Salvation Show, and religions don't get falsified. Falsification won't kill evolution any more than finding out Charles Taze Russell couldn't read Greek killed the Jehovah's Witnesses.