It's ongoing. An article isn't going to instigate a change mid-contract, no matter what a "smashing hit" you want to categorize it as. The current contract expires in 2021. People have their sights set on affecting that next contract. There is more coming though.
I definitely disagree with one of your points. Generally, the public don't know about the system. Maybe your circle does, but often even the teachers working with ALTs in public schools are unaware of just how poor conditions are.
Active ALTs, city hall, and the unions have long understood that the BoE and dispatch companies will not voluntarily make a single positive change. So it's a long drawn out process with constant resistance. This post was simply showing a public example of of the people standing against BoEs and dispatch.
All ALTs need to know that general conditions are unacceptable. Dispatch companies rely too much on fresh meat applicants who lack the life experience to know they're being exploited. This article definitely helped spread awareness of that.
Plus, this article hurt Interac's reputation in
Hokkaido. Some Interac staff complained to some ALTs that procuring new contracts was more difficult because of it. They could have been overstating things to make those ALTs feel like supporting it hurts their own employment prospects, or they could have told the truth, or a mixture of the two. But if a single school board refuses Interac a contract because their name was publicly associated with poverty, that would be a bonus.