The appearance of Benjamin Linus in the school where Locke is now working would suggest that this universe would not be related to the actual "original" Lost Universe but an alternate one, created by the resolution of a Loophole in the actual Loop on the events that lead to the existence of this story in the first place. In more detail, let's take a look at some of the events during time-shifts leading to the incident.
- Locke telling Richard to go see him when he was born.
- Ben taken to the temple after Sayid tried to kill him.
- Faraday telling Charlotte she has to leave the island.
- Miles leaving the island.
- Juliet Saving Ben. Harper, the therapist, tells her that she reminds him(Ben) of her.
- The Incident
Every single action that would have a significant change in the future didn't. In fact, when they shifted in time, they actually did what they had to do so that the events would unfold later as they should. Their actions had already happened, probably by themselves. They just hadn't done them yet. Now, this would mean that there is no connection between the explosion and the LA X universe, because everything just became a full loop and the events unfolded as they had already unfolded before.
The LA X universe shares some resemblance and some great differences to the "original" one. However, the most important one would be that the Island is underwater. At first, one would assume that this is the result of the explosion. However, had that actually been the case, Ben would have no reason to be alive and well teaching European History in the school where Locke is substitute, because he along with the island would've drowned. This universe must be the result of an event that has already happened in the past of that universe but that the characters have not yet done in the "original" universe's past. Someone will probably find/provoke the loophole, in this case referring to the loop in the random repetition of events that is time rather than only the "loophole" in a set of rules of conduct, then that will cause such an outcome that will drown the island and create an alternate universe to find balance. In this universe none of them, including Ben and Dogen, went to the Island since Jacob did not interfere in any of their lives and that would suggest that the lives of the candidates would have some major changes (Locke is getting married, Jack has a son, Hurley is the luckiest man alive) for better or for worse. The Loop could probably go back to the day Jacob and his nemesis had that talk while awaiting what seemed to be the Black Rock which could in fact be how Richard and the first outsiders ever came into the Island and started affecting it. Unless, the Island is, in fact, some purgatory or the Garden of Eden. Eventually, we will hopefully see EXACTLY how that universe came to be and what the rules actually meant.
Note: Though not completely clear, it is commonly believed that Jacob helped Locke survive his fall. If that is the case, then without Jacob he would be dead in this universe or his condition would have been caused by something else. No real answers are in-store about this, so I can't comment much on it.