An AVP universe is not a bad thing if done right, it could be great in fact! I would love to see an AVP film done right and despite what some fans say, there is nothing wrong with there being three separate universes, as opposed to an all encompassing one which can be messed up due to continuity errors.
Its a simple idea really and can be done quite fine, A pure Alien one with no Predators in existence, A pure Predator one with no Aliens in existence (skull was just an easter egg not a reference) and an AVP universe were the plots of both film franchises happened in the same universe and can feature both species and should hopefully open the way to a new AVP film with the previous AVP films being non-canon