Illfonic is not allowed to speak about upcoming content due to release schedules, the I.P holders, publisher, and the potentiality for delays or scrapping of plans.
The only ones we’re sure they wont do is the characters from The Predator due to childish reasons of not liking the film no matter how useful to the gameplay loop.
The AVP content is difficult to say but it’s likely they fall under a different license given that license is how Fox itself has separated continuity with Alien, Predator, and AVP all being its separate entities due to legal constraints. No, nobody told anybody in charge of continuity either. So despite it being relevant to Predator solo continuity and is meant to be canonical with it, is unusable without the extra license.
Various concept art of Predators do depict them with an AVP style spear. Various weapons like the plasma pistol are also inspired by the designs but of course aren’t actually them. You can also see helmets which are meant to be characters like Celtic and Wolf with Berserker seemingly inspired directly by the AVP set. Seemingly it’s a licensing issue and while the plasmacaster has been found and the shuriken it’s not meant to actually be used by Scar.
This is speculation territory here but it seems in all likelihood that they didn’t have the budget for the AVP license and so took Scar assets and simply will use them for their OC Cleopatra. We know she will come with the Shuriken and will need a plasmacaster likely using the rig intended for Scar. Scar also doesn’t have a unique roar so there was nothing needed in terms of sound to carryover especially given females have their own roar anyways. The shuriken was allowed to be used since it’s in The Predator freeing it up for solo material but since the OC is Illfonic’s priority rather than literally anybody else from the films or EU the weapon went to Cleo.