Even excluding the revenue coming in from sales, I can’t imagine Shueisha and Jump not compensating Usazaki in some way.
She was cancelled for reasons out of her control, without warning or prep time. Would be horrible if they just said “hey, I know you had a solid source of income because of Act-Age, but sorry, you’re on your own now”.
I obviously have no way of knowing they wouldn’t do this. Big cooperations screw over their employees all the time. I’d just like to imagine they’re giving her some type of payments aside from volume royalties until she finds a new series
According to Bakuman, WSJ authors have a yearly contract so they get paid (a little) even when they don't have a series running.
I know Bakuman isn't the best source, but I can't see any reason they would lie about something like this.
Speaking of compensation, I hope the other-language publishers also get some kind of redress if Shueisha indeed decides to pull the license. Viz will be fine either way, but Ki-oon is a relatively small French publisher with few big titles (according to their website, Act-age is their second most popular series), and Act-age 3 was scheduled to appear on August 27th, which means it was already translated and possibly even printed. Having to throw the entire run would probably be a significant loss for them (and also a total waste, so I hope they won't be doing this. Not doing reprints is one thing, tossing a whole bunch of perfectly good books in the bin is another).
