There are other theories ya know

Perhaps the ancients weren't driven or wiped out as previously suspected?
In Admiral Petrach's speech, he said that the Shivans might be exiles, forever roaming the universe, searching for a way back home. but then, what could be so powerfull to throw them out of it in the first place? From the FS1 cutscenes, we know that the Ancients fought them to a standstill and eventually lost nearly all the planets to the Shivans as they weren't able to hold them off forever.
But what happened when they lost the homeworld? I would think that if the Ancients were seeing the Shivans advance all the way, they would have something planned - something to deny the adversary total victory over them.
Perhaps, they prepared for the Shivans - when they were coming for them with nearly the entire fleet, a small (or perhaps large) fleet of acient ships abandoned the homeworld - moving instead into subspace; the realm of the Shivans. The final battle would not be on the Ancient's soil, but that of the Shivans. A layer underneath subspace or within in, perhaps controlled by the central nexus/hive mind for the Shivans - someplace which would now come under assault from the entire Ancient armada.
As we all know, if even a single ship collapses in Subspace, it closes it off. Now imagine the potential destruction such a fleet of ships could have caused even at that more stable, more basic layer of subspace.
Perhaps such a destruction is what forced them into the exile; forever to look for a way back home and yet never finding it. With a majority (but limited numbers) of fleets left inside of real space, any species would now become a threat till they could reach back home, something which might only be possible with the energy released from a dying star.
Perhaps this was why the star beyond Gamma Draconis was destroyed, along with many other stars - as an attempt (maybe even a futile one) to get back home. We only have a glimpse of one other system beyond the Nebula, something which we know is a Binary. But what of other systems, with single stars. Were they too destroyed by the Shivans? Maybe so, maybe not.
The Shivans could have just used Capella in the same way they did the star in the nebula - but why didn't they do the same to Gamma Draconis? Was it unsuitabe? Perhaps only bright yellow stars, much like that in Capella (or even Earth) was more suitable for the purpse - hence the Lucifer's run to Earth, in an attempt to wipe out the Terran fleet and pave the way for the Sathani to make a straight go.
That.......and i think im talking nonsense again :/