u know what i say? stop trying to up the ante. stop trying to "top" the last movie. more is NOT always more.
one of the very few guys who can pull off the "more is more" credo is james cameron, and u can forget abt him dipping his hands in the predator franchise. he's got bigger, and newer worlds to conquer.
i say, keep the new predator SEQUEL (yes, i still think it should be a damn sequel) to ONE predator, and have him go back to ONLY doing what his entire culture is about: hunting for sport. and give him WORTHY prey. we don't necessarily need a military unit as his targets, just some tough, resourceful badasses.
i've always wondered what it'd be like if we saw a predator hunting big game in africa. literally on safari. only this time, his prey includes the legendary masai tribesmen, who've been known to take down a lion with just a spear and some smarts. maybe even throw in a great white hunter or two. yeah, this would be a period piece, set in the early 1900's. where u can strip the technology away from the humans, and have them rely on their OWN hunting instincts and cunning. sure, it'd be pretty lopsided, but that would create a great opportunity for smartly-written characters, and not cardboard cut-out cannon fodder.
that's my 2cents' worth. and if this premise has been featured in some dark horse comic or fan fic, my apologies. it'll be merely a coincidence.