Will “they” be able to track down the bitcoins that “disappeared” from Mt. Gox?
If “they” can identity which ones and if those who took them try to use them, then it’s possible. Mt. Gox is also missing millions of fiat. So there is more to this than is being reported, IMO.
There is not such thing as a bitcoin. Anyone with any brains has already converted the ephemeral currency into dollars or commodities.
Bitcoin is going down fast. If you have any now, you'd better spend them today. Buy anything from anyone who will accept it. By this time next week bitcoin will not be accepted anywhere by anyone.