My assumption is that it'd be like an 87 Predator game mode where Arnold could be present to voice his own character seeing as Jungle Hunter and even old Painless are in the game. You'd have access to a jungle map as well and Self-destruct is also a game mechanic. So an intro-mission or a single player bit of content based on the original film would make sense. There's of course a helicopter and Human bad guys to shoot at which could be re-skinned to be the guys from the original.
While of course not affiliated, Frontier did something like this with Jurassic World:Evolution where they had elements of the 93 park which taught the player how to play the game originally. Later on they released a full Jurassic Park expansion, something like this could be happening here. You'd have content available based on the original film even if you couldn't get Arnold. We also know Jungle Hunter was modeled first so perhaps something they went with. There would be an opening based on the original film or that DLC would come out using these elements. I think they wanted to do single-player and they have assets and mechanics which seems like it would lend itself to single-player or an 87 themed mode that would primarily rely on Arnold.