This holiday will be big for Sony with many big third party games like Destiny 2, CoD WW2, Battlefront 2, and the rumored Far Cry 5/AC Egypt. With all these huge games I think Sony will sell 18m PS4 also lets not forget they have a good future line up with God of war , Last of us 2 etc.
As for the Switch it also has many System sellers to push it to Maybe exceed Nintendos expectations but I don't see the 3DS doing anything over 6m even with if it still has a decent lineup with Ever Oasis, Fire Eblem, Pikmin because it's pretty dated by now and will sorta compete with the Switch.
I can't see Nintendo passing the Sonys estimated sales unless they give the switch a $250 price or Pokemon. If one of the two happen then I think it will definitely happen but the way it is now probably not.