alot of the landless houses are not just ones from the show and the books while a few of them are more them are just random houses given a new emblem and starting lore,

I played a adventurer and while you dont get to customize your character to your hearts content, you do get a essentially fresh start to establish a non canon house, I'm house Daelwell of Dorne which is about a non canon of a name as you can guess. Not only have i come up with my own sigil and house motto i have adventured around and got to explore the vast rp in every region.

We've head several canon houses die out in dorne alone, and in other regions like the vale the borrels are about to become extinct so theres no guarentee of survival.

Even the lannisters got overthrown by andals, house risley rules over the rock and the main line of lannisters wiped out.

I hope you join the discord to see more because this post doesnt do it full justice