It is a possibility, it might be the reason why they stick to a modest 18M, but this scenario doesn't look impossible at all, if the launch of the Lite is strong, if the combinaison of Shield/Sword/Lite + the whole line up of Q2-Q3 works more than expected, we could have this :
FY2019 Q1 : 2,13 M
FY2019 Q2 : 4,5 M
FY2019 Q3 : 11,5 M
Total at this point would be 18,13 M