Way too many questions about what Nintendo does to make an accurate prediction. AC:NH came out in Switch's prime, whereas Splatoon 3 comes out in the last 1/3 of Switch's life, when people will start decreasing game purchases in anticipation of a generational leap with Switch 2 coming. But AC:NH could have amazing DLC content coming that enhances it's sales. Both games could have Switch 2 versions that boost sales as well. Way too many questions. If they released the same day in the same year then I'd say AC:NH wins easily, but that isn't the case.