OK, using the updated WiFi101 library, Feather M0 w/ATWINC1500, and Blynk together turned out to be so easy it’s embarrassing. Just start with the Arduino_WiFi_Shield_101 example and add the line:
WiFi.setPins(8,7,4,2);
before the call to Blynk.begin() (or before WiFi.begin() if you want to setup the WiFi connection yourself first and then call Blynk.config()).
Also, it doesn’t appear that your sketch needs the line:
#include <SPI.h>
I commented it out and things worked just fine.
Thanks.