That would be nice to have, but is hard to fit in the current game's design :/
Battle royale would require building huge maps, which the game currently doesn't have.
And the second and most important problem is the AI not being easily adaptable. It will have trouble playing on such large maps, and will generally not work well with this gamemode without tons of work.
As such, I would rather put this time and effort into making less demanding improvements on the game.