What happens to the new xeno? My take...

A good theory, but the Engineer in ALIEN had his chest bent outwards. But I like your idea of the Alien going to one of the other temples. Perhaps it does become a Queen, and lays an egg, or creates a Facehugger which she then uses to attack another sleeping Engineer in one of the other cryo stations found in one of the other temples. When the Engineer wakes up, perhaps he doesn't even know he was facehugged (like Kane did from Alien, just had bad dreams) and then because the Queen interrupted his stasis, he gets up and starts up the ship to take his cargo to Earth, or wherever he was going. But in flight, the new, smaller, more efficient Chestburster grows enough inside of the Engineer and bursts out of his chest - causing the ship to crash on LV-426. But then there's that acid on the floor beside the dead Engineer on LV-426. So, what could have caused that? Does this new Chestburster get injured in the crash somehow? Or does the Engineer try killing it and in doing do cuts it somehow allowing for the acid to burn a hole in the haul letting the newborn Chestburster escape? So many theories! Good topic!

it dies 2 days later from malnutrition lol

Your all forgetting that the eggs on the Derelict were covered in some kind of sensor field (the blue light which reacts when broken) so its highly unlikely the xenos could construct such a barrier nor would they choose to lay their eggs in such a place.

This adds to the theory Ridley himself has on the DVD commentary whereby he states its like an airship and the eggs are bombs that would be dropped on a planet as a form of bio-chemical warfare.

Ah! Good point, forgot that for a second. Yeah, I'm not sure! Perhaps Engineers come back to LV-223 to investigate and "harvest" the Aliens which have made a home there and from there, they go to take those Aliens elsewhere?

well the engineers had a factory on LV 223, perhaps Lv 426 was another factory that they had? because it could hardly be an emergency landing unless they got into a space fight with weyland and had to make a landing there? too many theories on how it links to Alien... and too many theories on how the proto-xeno links to the actual xeno...

Well the Derelict on LV 426 Contains the remains of a Space Jockey/Engineer suit. This means that the Pilot had a Chest Buster... One would think this would mean a infected Engineer would have had to been piloting that ship...... SPOILER FOR THOSE WHO NOT SEEN MOVIE...... - - - - But Prometheus had the last Engineer on LV 223 and he got Chest Busted with that new Organism..... and so could not make it to Pilot a ship... But....... David and Shaw made it to a Ship and flew away, now it never showed them getiing on the ship or wearing a Space Jockey suit.... we just see David tell Shaw there are more ships and he knows how they fly and so they then head off, next we see another Derelict take off in the distance. Now if the Engineers needed to wear the Space Jockey Suit in order to fly the Derelict, how does Shaw and David fly away in one.... If we assume 1st that a Human or Andriod can get into one of the suits and then get into the Chair, and then 2nd assume that the Xeno in this movie is the Proto Xeno. Then potentially a rescue mission send from Earth to find out about Prometheus could come to find that Xeno and at some point one of its crew end up trying to take away the Eggs it creates in a Derelict.... Or maybe some Engineers that Shaw and David incounter head to LV 223 to check what happened with Eggs on their ship, or then take Eggs from LV 223 and then there ship ends on LV 426... But then again the Derelict on LV 426 could have been there for years and thus the Xeno at the end of Prometheus is not the same as the Alien franchise Organism.

@BugHunter Indeed its so open... Yes the temple theory could work.... but then i would think when the Engineer woke up, he would have gone and woken up any other Engineers in other temples if there was any left... who knows.... Whats very interesting is the holes in 3 of the sarcophagus in the Orrey room of the Derelict and also what apears to be holes in the Space Jockeys that are pilled up in the halls. These holes are all in the chest region... Does that point to the Xeno being something that had already been around for a while something that maybe 2000 years ago or so got lose and caused chaos.... That would mean any Xeno from Prometheus is not the Proto Xeno.... Then again Ridley said this movie is about how Mommy meets Daddy and Lindelof said in one interview its about the Progentitor so who knows. Again its all still left very open..... even more so now ;)

The SJ found in Alien looked like it had been there for thousands (maybe millions?) of years so I don't think the events in Prometheus can tie into Alien directly can they? The dates wouldn't add up.

The Xeno on LV223 must surely play it's part somewhere though. It just seems that no quicker has a connection been made to it's "canon" that it becomes stranded again and cast in some sort of limbo. Unless... the lifecraft sends out it's own beacon...