Another Possibility

While the speculation of our new enemy in Halo 4 continues, Id like to point out that this might not be what we expect. While Im perfectly fine with the new enemy being the Precursors/Forerunners,it could be something completly different and unexpected.In the Halo CEA terminals(namely the “Silent Cartographer"and Assault on the Control Room”) 343 Guilty Spark speaks of his attempts to make contact with the other Installations;only recieving messages from Installation 05,probably speaking of a Flood outbreak or some other problem.Next Spark encounters a new race(or their crashed vessel) on his Installation.
These beings appear to not have had contact with the Forerunners as Spark cannot translate the message.Their ship also has relative same atmosphere as his own Ring.
It`s also stated that other vessels could be nearby.

Now the theories;since the Forerunners built the Halos to support life on them. So its possible that a species could have advanced to sentience and used Forerunner technology to advance.This could lead to the Flood outbreak that compromises The monitor of 05 and also made for the communications gap.Then these beings could have used the the technonogies to escape to Installation 04, leading to their crash landing.
This would explain why the language was unknow and Guilty Spark couldn`t translate the message,because these beings were un heard of.

But this is all theory so I`ll leave this to the community. Just had to clear that up.Thanks!

Yes, but what if what was in the ship was not our enemy? True, why would a Forerunner run into the ring and Guilty Spark not be able to understand the language. You make a lot of good points OP. You do have to take in consideration we know very little about the precursors cause when the rings fired it destroyed their technology and their buildings as well (for all we know).

Forerunners are portrayed as good people in the books but where is the side we haven’t seen? I really wanna know more army wise and what potential do they have at their disposal. So many questions so very few answers.

We will see soon enough.

> Yes, but what if what was in the ship was not our enemy? True, why would a Forerunner run into the ring and Guilty Spark not be able to understand the language. You make a lot of good points OP. You do have to take in consideration we know very little about the precursors cause when the rings fired it destroyed their technology and their buildings as well (for all we know).
>
> Forerunners are portrayed as good people in the books but where is the side we haven’t seen? I really wanna know more army wise and what potential do they have at their disposal. So many questions so very few answers.
>
> We will see soon enough.

Thanks for posting! And as for our lack of knowledge of the Precursors I do have a point to make.
The Forerunners did make contact with the Precursors(i.e the war) and that bineg said they had petty good understanding of one anothers language.Take Primordium and Cryptum for example,both times we hear from the last Precursor"the Timeless One" and he seems to be very capable of communicating to others.That being said their language would/could have been arcived along with other races for communication purposes.
But like you said,we`ll know soon enough.(and I have thought of the possibility that these might not be hostile as you mentioned)