I'm wondering how/if the Clans funerary rights will change when the get to the lake. ThunderClan probably won't change, because they just bury their dead. RiverClan probably won't either, or at least not much, because they do have a river in the Lake territories to send their dead down. Unless it feeds into the lake instead of away from it, in which case they may have to change things a bit so their dead don't accidently wash up on the Gathering Island or other Clans' territory.
But ShadowClan and WindClan would have the most trouble one they get to the lake. ShadowClan leaves their dead at Highstones, which obviously won't work if they move. Maybe they'll leave them at or around the Moonpool, but will there be enough stones lying around the Moonpool to cover the dead? Or will they have to adapt a bit of ThunderClan's funerary rights and bury them, at least in a shallow grave of some sorts if not completely?
WindClan uses the Carrefour to leave their dead to other predators to eat. But once they leave the forest, there won't be a Carrefour to leave their dead at anymore. Maybe they could sort of "make" a new one once they get to the lake by talking to the local predators. Perhaps maybe that's even how the badger issue that ThunderClan has in canon gets dealt with, by WindClan promising to give their dead to the badgers to eat as long as they leave the Clan cats alone?
This is something that I think would be a fun sort of side-topic when we get to the part of the second arc where it'd be most relevant. I will admit that I didn't actually think about this aspect of the cultural changes, so I'm glad you brought it up!
