People won't stop having children. Population will increase EXPONENTIALLY, and a massive rate. We'll run out of the reagents necessary for the millions of daily Reincarnations, and getting the required spell slots, casters and infrastructure would be insanely difficult. And what will we even feed all those people?
Look, I hate IRL Malthusianism and I would also love to be able to give everyone access to eternal life. But DP won't allow self-replicating infinite-use magic items or infinite Wish loops, and without that any kind of "make everyone live forever and come back from death" plan is just utterly impossible for basic logistical reasons.
The Fungus Forge can produce people who can cast reincarnate, and we can make more Fungus Forges, so getting the spell slots is no problem.
The reagents can be grown, so while it would be hard to set up, considering a large part of our population are farmers, growing the plants to extract the rare oils required from should be doable, and as the workforce expand as much as the demand, the supply should be able to keep up with the demand, as long as we have space to grow the reagents on, and with Underdark plants making it so we can grow things underground, our available space is pretty much infinite.
Food is the same, with Underdark plants, space travel and the Plane of Earth, we have a limitless amount of places that can be turned into farmland, so we aren't likely to run out of food.
Arguably we could build more Fungus Forges and tax the growing population to fund new rounds of Reincarnate-casting Leshies. Fine, let's accept that theory. I'm not sure the costs work out, but whatever. Maybe peasants will all get richer and it'll work.
But
@tarrangar, how will we solve the food problem? Or the reagent problems? Sure, the Planes are infinite and theoretically have infinite resources, but most of that infinity seems utterly uninhabitable and more or less useless.
There's lots of ways to solve the food problem, we already have space travel, and we have access to the plane of Earth, we could set up portals in space and literally build planets if we wanted, we of course wouldn't as a planet is a terribly inefficient use of resources, but building asteroid farms aren't so inefficient, and there's space for a near endless amount of them around the sun, and if we ever fill up the space around our sun, well there's plenty more suns where that one came from.
The asteroid farms would need massive glass domes to keep the air in of course, and we would probably have to research how to tint the domes to keep radiation from getting in, but once that research was done, we could literally build endless domed asteroid farms, they don't need to be small either, although it's probably better to have each individual dome be smallish, with just lots of connected domes with doors between, so you don't need to just break 1 dome to destroy a whole country worth of domes.
And yes I know it will be quite some time before we can mass produce that kind of thing, but Planetos at the moment have a quite low population, and there's still plenty of easier colonization targets, so even if we mass introduce reincarnation, we have centuries, before we need to begin building domed cities around the sun.
The thing is the Old Gods can already do that though the forge, it requires their direct will so they won't do it while the Others exist, but if you guys can deal with that the forge could reincarnate fine, though they would not work for money.
The Forge can also make beings that can cast reincarnate, a Druid creature with the spell is below CR10, so as long as we can build more Fungus Forges, we should be able to make any amount of reincarnators needed.
It's completely impossible. That's all there is to it. Impossible.
Population growth will always exceed the capacity for Reincarnation.
I'm trying not to be a dick, but this has been explained previously. Multiple times. You have got to learn to let things go, dude.
DragonParadox just outright said this statement is false, the Old gods can reincarnate any number of people, sure they wont take payment in money, but if instead of it being them directly doing it, it's Fungus Forge creatures doing it, then the Fungus Forge creatures will probably take payment in reagents, so they can create more of themselves.
All evidence is that while yes reincarnation would result in exponential growth, seeing as we can build more Fungus Forges, we can equally cause our amount of Reincarnators to exponentially grow.