One thing that's similar to NDEs, but probably not exactly the same thing, that's become interesting to me is people who are near death or dying, and instead of having NDEs of going into another realm, they hallucinate here on Earth.
I think pretty much all of my dying relatives have mentioned people who are already dead having come talked to them, even though they generally have to be reminded that said person isn't alive. Interestingly, they've never seemed concerned upon being told this. It's also not made a difference on the mental acuity of the person. A couple of my grandparents/great-grandparents were completely lucid, but still saw passed loved ones or friends, while others were senile (but I find that's more expected in that case). The weirdest one, though, is that my grandmother (who died) and an elderly friend of my family (who almost died, but ended up making a recovery) both saw numbers and writing in a strange language on the wall, and asked about them, pointing to locations that were completely blank. Could it just be some kind of chemical reaction in the brain as it preps to shut down? Sure. But I've had relatives who lingered for several months or years in a diminshed state, and still saw these things toward the beginning. Even on a spiritual level, one could question, if it was real, if the people the dying see are really those individuals, or guides who take that shape to help comfort those before they pass.
That said, like others have already said in the thread, I don't think people who experience NDEs are seeing Heaven/Hell. If the visions are real, they are probably in-between places between realities. When an NDE occurs, you're probably still locked to your mind, and I question whether a human mind can even comprehend Heaven or Hell, or a possible third place where you wait for Judgement. There seems to be distinction between mind, body, and soul, and, despite the fact they all interact and mesh heavily together, it's likely only an unbound soul can truly understand the beyond.
2. Suppose someone did see Hell. Well, seeing is believing, and they will repent out of fear rather than wanting to seek a connection with God.
This leads to an interesting theological question: Would seeing Hell prior to having a relationship with God prevent the average person to even being able to obtain repentence and salvation?
A connection with God is the most important, as well as most overlooked, property in salvation. If one only attempts repentence because they are consumed by fear of Divine Punishment, can that essentially sever any possibility of forging a connection? Of course, through God all things are possible, but I still find it an interesting question of if, when faced with a true vision of eterenal divine punishment, can repentence occur? Because otherwise, wouldn't all but the most deranged repent once they are put in front of the Lord to be judged?