Imagine if 7-11 or Kum N Go offered a free weekend of gasoline..........
Interesting thought experiment.
With gasoline the lines would be long with people in a frenzy to get their free gasoline.
With this EA announcement the impact will be small.
The reason isn't because EV's are a small percentage of the cars on the road, although that is part of it.
The real reason is that charging an EV is so cheap already, getting the "fuel" for free isn't all that much cheaper or enticing. In my case the nearest EA station is 25 miles (31 mins) away. Is it worth it for me to drive for 30 minutes to get maybe $2 or $3 of electricity for free. Nah I have better things to do with my time. However if the gas station at that same location was offering free gasoline and I still had a gasoline car (I don't) then saving $50 would be worth the trip.
In fact the two closest Nissan dealers to me which are much closer than EA offer free rapid charging 24x7 (and have been doing so for the last 9 years). Those stations get very light use despite being free. As EV drivers we already have access to free rapid charging close to us, and because of the low cost of charging at home we simply don't bother to take advantage.
For those of you who have read Predictably Irrational offering gasoline for say 10c/gallon would have a much bigger effect than offering it for free. When something is free most people take what they believe is their "fair share". When something is very cheap they take as much as they can reasonably afford or carry which is much more than they would take if it was free.