The leader of one of the largest, if not the largest, drug cartels in the world - the largest producer and "exporter" of fentanyl to the US - is taken out by Mexican military/LE.
The action may have been supported with intel from US agencies.
The appropriate reaction is, obviously,

.
How big of an impact will that action have? Who knows - and certainly there are many other steps required/available to reduce the destruction caused by drugs like fentanyl (greater border security, enhanced law enforcement efforts, locating and arresting cartel members within US borders, etc etc - the list would be a long one, and any reasonable people could add more to it.)
Minimizing the impact of drugs like fentanyl will take much, much more - consistently and thoroughly - but, clearly and obviously, taking out the cartel leadership at its head is an important, positive, and necessary step.