Just because bacteria have become resistant to their first line antibiotic does not mean we don't still have a choice of antibiotics with which to treat. In my lab the bacteria we culture from patient specimens are subjected to a whole battery of antibiotics to identify exactly what they are sensitive to. For example, MRSA could be treated with vancomycin, tetracycline, linezolid etc. The downside is that some of these alternative antibiotics may be less effective, and the doctors are more dependant on lab results to know how best to treat.
As for the the article, very interesting. It's good that we are identifying more novel antibiotics, most of our current ones are just variants of a few different types (for example all the beta-lactam's are just variants on penicillin) which has contributed to antibiotic resistance. The other lesson to learn from past experience, is that if this does prove effective, we don't abuse tis compound, again allowing resistance to evolve.