The shops will remain but not multiplayer, leaderboards, etc.
Nintendo has announced that as of May 20, 2014, "certain online functionality" will end for many Wii, DS and DSi titles. This change will not affect the online stores. Discontinued functionality examples include:
Online play and matchmaking
Leaderboards and tournament data
Sharing of user generated content (ghost data, user created levels)
User exchange of in-game items or characters (Global Trade Station)
Free add-on content or downloads (new levels, in-game items, Mystery Gifts)
The full list of affected titles is available here.
Author: Brian Hoss