This may have been said already or you think shut up this is bollocks but just think for a second. Is the new Locke smokey??
1. He knows exactly where to go to see the old smokey (himself) 2. When Ben summons the monster who comes wondering out the jungle...Locke! (not smokey like before) 3. When Ben sees the monster Locke dissapears to supposibly go find something to get him out. If this was the real John Locke he would be down there in a shot wanting to know the secrets of smokey!
However, I too think this theory is most likely unlikely but it does seem like a possibility. And if not smokey then an image created by the islands power!