Hm, so far the only improvement we know of is that it has Japanese voice acting. I'm assuming that will be updated into the PS4 version? Either way, I kind of doubt it will be as great of a port as expected. Some people were acting like it would be an Ultimate edition, with the Switch carrying both the 3DS version and the PS4 version on one cart. I'm not saying it won't happen, but that sounds like such a superior version that I just doubt it.
Hopefully it releases on Switch in 2019 for the West, too! Don't see why it wouldn't.