The number will have to grow exponentially to cover all your M3's and hopefully some of the Tesla owners become more courteous and not hog them.
Tesla is doubling the number of Supercharger locations in North America
Strange that we haven't seen more of an uptick yet, though:
This graph makes me very happy!
Hopefully we will soon. Honestly, I think it just comes down to how much they're investing in their production lines. Because they're going to keep their supercharger production lines running at capacity regardless, and they're going to install every charger that they make regardless. A linear slope, to me, says little new investment in supercharger production.