If I take a handful of salt and wait for an infinite time will it become a single crystal? That pretty much says it. 
Suppose I have some powder of $NaCl$. It is kept in contact with itself in vacuum. You are free to remove all the disturbances that bother you.
Is that true that, well, there exist a ($\mbox{very}^\mbox{very}$ large) amount of time $T$ that for every moment $t>T$ you will have a single beautiful crystal with 99% probability.    
 A: If you wait long enough, it'll become a bunch of iron (assuming it's confined so that the atoms can't evaporate off as Marek pointed out). After all, an iron nucleus is more stable than any other nucleus. The probability of the other nuclei tunnelling together to form a big hunk of iron is absurdly low, but it's not strictly zero. If you wait long enough, it'll happen.
A: Technically, if you have infinite time to wait, then yes. This is based on the standard "if it isn't forbidden, it is compulsory" idea of QM. However, as other answers have correctly pointed out, there are other potential quantum fluctuations that are also available and may be more probable. Combined with the unlikelihood of the desired quantum fluctuation, in any practical sense, the answer is no because the universe will end before this occurs.
Also, with regard to the last line of your question, which is slightly different, the answer is a resounding no. Although you can conceivably get a single crystal at some very large time T, you will not retain a single crystal for all time t>T because another fluctuation will destroy it eventually.
A: If you wait very, very long then your NaCL will be part of a black hole, for this will be the only entities in the Universe in the far future, at least according to our current understanding.
Then, eventually, these black holes evaporate and your NaCl will be part of Hawking radiation.
In the ensuing thermal ensemble you will have random fluctuations. If you wait long enough then, indeed, you have a probability arbitrarily close to 1 that one of these random fluctuations will be that your original NaCL powder forms a perfect crystal, or that some monkeys type the work of Shakespeare ;-)
So in short, the answer seems to be 'yes'.
