I think it all depends on development and scheduling.
There are a lot of first party titles on Nintendo's end that are releasing this second half of the year.
Animal Crossing is the 2nd biggest title they've got coming out later this year though. If it were just a matter of scheduling, you'd think that it would be Link's Awakening or even Luigi's Mansion that got pushed back. Why would Nintendo skip a holiday cycle for an evergreen title that'll easily sell 10 million?