I think the circle will close and we already saw pieces of that. The flashback to the epic mib/jacob dialogue was imo the flashback to the "start" of the guard(god)generation jacob, the generation the lost series is about. in s05 final u can see how jacob "furnish" his new home: -making the tapestry - fresh fire place - jacobs eating fish and mango like he was hungry a long time - starring on the ocean like he finally are placed
i think when jacobs starts his new job as guard he immediately began to find new candidates because of this really long process. he starts ambitious and pilotted the blackrock to the island where richards on who was imo one of or the first candidate. that confirm the fact that richard got the special not-aging effect and is or better was some kind of the right hand of jacob as ben said to sun: hes some kind of advisor.
so here we are, jacobs the new guard and samuel is the natural opponent of the guard. notice that when unlocke speak with sawyer and told him there is no one need to protect this island -but thats obviously wrong and just blind rage of the long year trapped mib-. thats why samuel went to the new guard because hes pissed off the ship and said "u havan idea how badly i wanne kill ya?". jacobs seems not afraid but a little bit new in this role when he said "yes"
in my opinion there will be a new guard and unfortunately -.- it will be jack. so much signs are speaking for that. not at least the pilot scene (which is one of th scenes that ull see different when u saw 6 years lost) where jacks at another place, like the traveled through time kate after incident - middle in the jungle, not at the plane.
and the final episode will end with the start of jacks life as the island guard! dunno who will be the new mib (still too los for that ;-)
i hope that we will learn more about the 18th century and hopefully about the beginning of jacobs career ?