I've written up a few outlines for my version of a AVP3, although only one has made it to screenplay status. The only one that I remember right off the top of my head was probably the worst idea I've ever had. It was kind of sort of based on the Xenogenisis comics for some ungodly reason. It started out with a predator manhood ritual going completely out of control and spilling into a nearby colony. Eventually the entire clanship comes down and decides to beam-spam the Hive, the Colony, and the Preds still down on the planet. One of the predators manages to escape in a shuttle and just as he docks in the mothership, he realizes that the shuttle is crawling with predaliens. The clanship crashes just as Colonial Marines arive on the scene, but not before calling in the predator Military (think AVP: Extinction).
Huge three way battle breaks out, and it all ends with full scale nuclear exchange between the marines and the predators. This was all supposed to happen montage style during the opening credits and probably would have cost more than all eight movies combined. So now the predator's secret is out and Earth decides to go on the offensive using -get this- genetically modified aliens with guns, and the queen is a cyborg with missile launchers and plasma cannons and crap. A colonial marine ship transporting these crimes against the fandom crash near another colony where it just so happens that another predator manhood ritual is going down. Several disgraced predators are being used as bait to lure the aliens out of their hive And -KAGASP- one of the predators being used as said bait is the dumbass who let all the predaliens on the clanship. In the insuing chaos, the elder predator is killed and "Our" predator escapes....but is blinded by a plasma weapon going off right in front of his face. It's temporary, of course. He is found by generic heroine number: 2580, and turned in to the colony, from here on in, it's basically the original AVP Miniseries except "MOAR UBER!!!!11111111". Of course the colonial marines (led by Generic Heroine: 2580), the surviving predators (led by Dumbass) make a heroic last stand against not only the normal aliens, but my bastard mind children.
The above was basically my attempt to find out how much fan wank and epic battle scenes I could shove in to one movie.