Sorry if this has been posted before I do not read these much. I have had many discussions with friends about these last few episodes and may have a few different theories. As far as the little blonde haired boy that "John Locke" aka MIB finds in the woods, would it be plausible that this could be Aaron years later? Everyone obviously feels that Aaron has a major role in Lost, so I believe they are going to have to bring him back in the spotlight somehow. Another theory about the little boy could be Jacob as a child.
There was also a split second when the MIB yelled "you can't tell me what I can't do!" (something John Locke has said many times throughout the series) Could this have something to do with some sort of weird mesh between MIB and John Locke?