I'm not sure FFXV will sell over 1.5m but I'm pretty sure Splatoon won't so unless FFXV underperforms greatly, which it could, I don't think that's going to happen. FFXV's performance depends a lot on when it comes out (before/after Kingdom Hearts III, FFVII, DQXI, etc.).
I agree about FFXV at 1.5 million, but Splatoon? I mean... of course will. Splatoon will sell nearly 1 million only this year. then, will easy sell other 500k in 2016 / 2017.