3ds numbers might be enough if enough people buy it as new leaf and XY nearly hit that number and is still somewhat selling at 4.6 and 4.4 mil respectivly.
as it gobbles up the vita market though we could see the switch hit DS numbers.
at 15 mil by the time pokemon comes out I'm confident that pokemon switch will hit 5 mil. splatoon? well.. it MIGHT struggle due to it being a extreamly early title when there are supply constraints...