I personally think they just get reincarnated, because of their connection to Kingdom Hearts and the worlds. Or something.

 

 

Nah, if they die their light is snuffed out, That's why they need to be protected.

I personally think there are more than 7:

 

but seven are either the most radiant of them all

or the only 7 that are known of or 7 that are confirmed as pure hearted

or 7 current ones (so if one dies another one gets born)

Like you said reincarnated. Or everything hits the fan and everything becomes unbalanced and hell unleashes over the kh universe

Nah, if they die their light is snuffed out, That's why they need to be protected.

 

Yeah, true! Smart thinking!

I could never see them dying since the bulk are Disney characters, but I would assume like most things their Pure Light is born again in a new PoH (like if Snow died, then you visit a Tangled World and see Rapunzel just being born and she becomes one, something like that).  Like I understand they need to be protected, but them living forever (even for Disney characters in KH Sora and co all age it wouldn't make sense for them to be 40 visiting a 7 year old) seems like a stretch, where new ones would have to rise, but similar to I said you've have to wait for the new one to be born and grown up to really harness her power so it'd leave a vulnerable gap til that timecomes

Least that's what I presume 

I could never see them dying since the bulk are Disney characters, but I would assume like most things their Pure Light is born again in a new PoH (like if Snow died, then you visit a Tangled World and see Rapunzel just being born and she becomes one, something like that).  Like I understand they need to be protected, but them living forever (even for Disney characters in KH Sora and co all age it wouldn't make sense for them to be 40 visiting a 7 year old) seems like a stretch, where new ones would have to rise, but similar to I said you've have to wait for the new one to be born and grown up to really harness her power so it'd leave a vulnerable gap til that timecomes

Least that's what I presume 

Well.. Kairi ages. So, unless she randomly stops getting older, I think you're right.

Eh, i don't know. If they die, they die (Please don't kill me). That's life.

A lightbulb burns out or something.

Well, since we don't know for certain if something like that would happen, I really don't know what the consequences would be.  I imagine though, that if one of them died, part of the worlds would be consumed by darkness, or, let me specify, the darkness would have a stronger influence in the worlds, since the Pure Light would die out. But, since children have light within their hearts, I doubt that the Pure Light can ever truly be snuffed out.  But it's an interesting topic to talk about.  But I don't think a Princess of Heart would die, because Disney wouldn't allow it, so it's a tough cookie to swallow.  But then again, maybe Disney would let Nomura have the liberty to decide the fate of the Princesses.  No one really knows.

I think the case is kind of a mix??? Like, it depends on HOW they die.

 

If it's a natural means (old age, fire, drowning, exsanguination[blood loss], asphxiation, etc.) then they just get reincarnated. The light goes on to someone who has a pure and bright enough light to take on the weight and the universe isn't in peril or anything.

 

If it's a supernatural means of death (Heartless, consumed by darkness, Keyblade, etc.) then the light is snuffed. Since Xehanort or any of his buddies can deifnitely cause a supernatural means of death, the Princesses of Heart definitely need to be protected. Once the threat is over everyone can relax until the next big threat raises its head.

 

But honestly why are we even talking about this no way they'd kill off a disney princess.

...

right?

oh jeez Kai ain't a disney princess I'm worried now

Their light will come out ....?

I don't think it would necessarily be reincarnation, but I believe that the day a PoH dies is also the day a new PoH is born. Either that, or you better hope the PoH are timeless creatures.

we get new poh

You assume that there's any power on earth that's CAPABLE of killing one of them.