How will they handle land claims and naming rights?
From the trailer, we know that the game takes place on a single roughly Earth sized planet, and we are meant to explore and build on that planet. You can see characters of various species flying around on giant birds, working together to construct buildings, etc.
I don't think we're gonna run out of space to build. On the real Earth, only about 50% of it is settled, and the vast majority of that is agricultural fields and pastures.
The biggest potential problem I foresee is: when you start building a base, do you now own that land forever, or is there some kind of tax you have to pay? How many acres of land per player can you claim? Is it simply first come, first serve? This isn't an issue in No Man's Sky due to there being infinite real estate of each biome, so each player base can be a 1km radius. But in Light No Fire, being in close proximity to npcs, dungeons, oceans, or resources might be valuable. In a worst-case scenario, you could have land scalpers in the game trying to profit from this with alt/bot accounts.
I think if we're going to figure out land rights in a non-toxic way, the game will need robust mechanics for who can build where AND it will need both small and large guilds/clans/kingdoms of players that we can join. How the building part of the game looks and feels will be heavily influenced by how big the land claims are, whether they take resources to maintain, and how the player guilds are set up.
Another thing is who gets to name the mountains, rivers, oceans, etc. that we come across? In NMS, the first person to see a planet gets to name it (which is supposed to be permanent but sometimes gets reset by glitches). For LNF, I'd prefer if there was a way for the community to rename biomes using some kind of voting system... as in let the players who actually have built bases in that region decide what it's ultimately named? Because what if there's a perfect spot for building a village, but it's located within the Six Seven forest?
What would you choose to name your mountain or settlement?