So, I read a blogpost (if you are the poster, I'm sorry that I can't remember who you are) that theorized the new locke may be Widmore in disguise. I personally don't believe this, but it got me thinking...
In season 4, Ben and Widmore mentioned not being able to kill each other and a set of rules that they seemed to live by. Jacob and his nemesis also seemed to not be able to kill each other, and if the bad guy was searching for a loophole, he must have been trying to break some sort of rules.
What could be the significance of this? I don't know. It seems that if Richard took Ben to get "healed" when he was shot, he may have a piece of Jacob or his nemesis in him, which could be the loophole. Or maybe it's because Ben wasn't supposed to return. Or possibly just that nemesis guy had to get someone else to kill Jacob. However, maybe there is more to Widmore and Ben. Maybe they are, in some form, related to/sided with/reincarnations of Jacob and his nemesis.
I also think that there are 2 different smoke monsters, a black one (nemesis) and a white one (jacob, and the one that Locke saw in season 1's "Walkabout").
Let me know what you think!