It probably will never be ported. For Capcom licenses to use the intellectual property from the Aliens and Predator movies have lapsed and probably won't be. Emulation is our best option short of buying one of the few remaining original arcade machines boards.
First they would have to remaster the graphics somewhat to have no pixelations whatsoever and in Hi-Def like they did with one of those street fighter 2D games ported for Xbox Live Arcade.
The original arcade resolution was only 384x224, which is a very small.
And not only do they have to smooth out the graphics for an updated port, Capcom would have to put in extra modes and crapload of unlockables, otherwise it's just an "Arcade-Perfect" port with nothing more to offer which had already been done so through emulator software (though not entirely legal of course).
Thus with no incentive from anyone that has already played through the entire game a decent number of times to purchase it for a premium price of 10-20 bucks.
If it does happen as an Arcade-Perfect port then it serves nothing more than a cheap discounted 5 bucks or so purchase as gratitude to the fans that still cared about their version of AvP and that they finally cared enough to try.
And also, it would be so that those people with just the Rom(s) and Emulators can then purchase a "Legal licensed" version of the game easier without spending 300 dollars or more all for the original Arcade board and the means to play it-
I.E. SuperGun JAMMA to TV converter which costs like a fortune, and not worth the money just for this 1 Arcade game specifically