First off, The first battle royale game I know is from 2012, So not original. Second, Battle royale is a concept and type of game. Should Doom sue every gun including game just because they were the first popular ones to do it? NO. Why sue black ops 4. It may be an awful game, But no copyright infringement
It won't win. On what basis would it sue it for? I'm assuming it's because of the battle royale aspect, But battle royale is too broad of a term that it can be considered a type of game on its own. So, Simply put if Epic Games sued Treyarch, They would not win. So they shouldn't.
Just because its a new battle royale doesn't mean its coping fortnite. I know fortnite is great and all but like really bro. So remember when you thought pubg was like why u copy us but really they just came out at like the same time and there both battle royales that doesn't mean ur copying
A person or entity cannot own a genre and the battle royal platform has been around for quite awhile. No intellectual property has been stolen, And if someone were to make the claim, Then there are a LOT of developers who will be suing Epic Games for intellectual property rights.