Nintendo has announced that they will no longer support the Wi-Fi Connection past May 20, 2014, so this should serve as a reminder for those who might still be interested to "complete" their Tierkreis experience. (Or, any other DS/Wii titles that rely on the same feature, for that matter.)
On that note, this decision feels rather premature, since even newly released 3DS/2DS continue to have backwards compatibility with DS titles, but that's corporate decision-making for you.
Have fun with Tierkreis' Infinity while it's still up and running, everyone.