According to the article at least, that is essentially what they did. But their model was based on earlier years when there was higher projected growth, so the budgets were set too high as a result.
Personally, as long as the final installment in the FF7 Remake trilogy is made with the same budget as the first two and ends on a satisfying note, I'll be happy. A good ending gives the trilogy as a whole have more lifetime sales than it would if part 3 makes the first two less good in retrospect, i.e. the Mass Effect 3 effect.