According to Serebii.net, after March 31st, it will no longer be possible to check-in to Pokémon Shuffle!!!

[Tiger21820]

Yeah, for some gosh-forsaken reason, Pokémon Shuffle's online is handled separately from Nintendo Network (Which will still work for now), and once that date passes, checking in will no longer be possible until some genius hero creates an unofficial server that will handle Pokémon Shuffle online data!

So, there is a HUGE problem that can come from this: Special Stages require checking in in order to play! Once you check in, Special Stages can be played offline! And here is where the huge problem lies:

IF YOU CHANGE THE 3DS TIME AT ALL, YOU WILL BE LOCKED OUT OF SPECIAL STAGES UNTIL YOU CHECK IN AGAIN!!!!! ONCE THE SERVICE IS SUNSET, YOU WILL NEVER BE ABLE TO RE-ENABLE SPECIAL STAGES WITHOUT HACKING EVER AGAIN UNLESS SOMEONE CREATES A NEW POKéMON SHUFFLE SERVER, AND ALL CONTENT EXCLUSIVE TO THOSE SPECIAL STAGES WILL BECOME PERMANENTLY UNOBTAINABLE!!!!!!! THAT IS VERY, VERY BAD!!!!!!!

If you want to continue playing special stages and hopefully complete your collection, YOU MUST NEVER, EVER CHANGE YOUR 3DS TIME LIKE YOUR LIFE DEPENDS ON IT!!!!!! IS THAT CLEAR???????