I would bet it'll be either MindCrystal or SpiritCrystal, since they both sound incredibly lame and therefore are prime picks by Nintendo's standards. The former sounds like some Final Fantasy key item, and the latter has little euphonic value. To quote a GameSpot thread regarding this very question, we'll get Pokemon Crystal Meth if we're lucky.
However, seeing as there was no Yellow remake following FR/LG, one could doubt that there'll ever be a Crystal remake.