IMO, both of the two creatures are perfect the way they are. Makinmore changes would just be trying to make more money and milking the two franchises for all they're worth.
Though they could do some small changes though such as newer weapons for the Preds since it wouldn't affect the mythos that much (though nothing too ridiculous). This would actually be better than just making what they already have bigger just to look more cooler (AVP Plasmacaster and Wristblades).
And as for me, additions to the Xenomorphs are sometimes good (without changing the original). I accept the ones like the Predalien and Praetorian (to a lesser extent) because they will be able to fit in without feeling out of place, but no ravagers or cystic warriors.
"There are five possible operations for any army. If you can fight, fight; if you cannot fight, defend; if you cannot defend, flee; if you cannot flee, surrender; if you cannot surrender, die."