This seems to represent a real adaptation of the malaria parasites, and if it spreads we have a big problem. There's nothing on the horizon to replace artemisinin. True, different areas may still have parasites susceptible to mefloquine or something else, but over time the resistance spreads. We may wind up going back the bad old days of DDT.
There are a few things I wasn't expecting in the report. They are able to do genetic matching, and find that 1/3 of infections are from multiple strains of plasmodium. Their data analysis excluded about 3% of patients whose malaria clearing rates didn't match a nice log plot. That could be bad measurements (not unheard of) or might be something interesting in how the disease works--I'm not expert enough to guess. And they were worried because a reduction in malaria rate meant that patients tended to lack resistance (nobody get immunity, I guess) and might get sick faster with something there was no treatment for.