More info on modding:
there are some files lingering around the game install at the moment, called "GameCustomInstalledBundles"
inside the files

Inside it is just the party royale posters, but i suspect thats just them testing it

https://twitter.com/Lucas7yoshi/status/1330759287996604419

[1/2]

the most DAMNING info in this is the the name of the plugin, its a randomly generated text.

That means there can be MANY of them without any names clashing.

More info comes from the API:

valkyrie content plugin has "Create" permission, so you can create these plugins(for user)

okay the [1/2] was wrong

the name of the plugin tho is similar to how they store other, user created content.

So all this stuff just yells to me "user created plugins" = "modding"

and the poster thing is just icing on the cake.

How much we can mod the game is NOT clear, maybe its likes scripting, maybe its assets.

I don't know, but this does seem like its something big coming up, and even just scripting would be big.