New Mass Effect Teaser Trailer

What I would like to know is what is that artificial disc/ring around the star in the middle of the trailer (when the first contact protocols come up)?

There was no such thing that we knew of in the Milky way during the OT. It looks like a structure built by a machine race. The geth were planning on building a Dyson sphere beyond the Perseus veil. Was this their handiwork? The fact that it comes up at the rim of the galaxy near a nebula (Possibly Messier 76 -- the little dumbbell nebula in the constellation Perseus?) may mean that it was made by the geth. It also shows up before the sounds of the Reaper War, so I think that implies it wasn't built post war. (If it were built post war that would definitely imply it has been a lot longer after the OT than Shepard's expected lifespan.)

Why would a geth "planet" be in the trailer? Maybe the Geth are alive beyond the veil. Or maybe their civilization is dead and we will explore it at some point.

I saw some people (Hrungr and others) post that the Mudskipper may not be our ship but a shuttle. (Sorry, too lazy to find the posts.) That would make sense as it doesn't seem big enough for long term living quarters. On the other hand, it looks too big to fit in the cargo bay of the Normandy, so I still wouldn't get our hopes up that it's Shepard's new Kodiak. I think it may just imply that our potential new PC (or their employer) doesn't have the resources to have a spacious ship. Maybe they do hot-racking or something.

Another reason I don't think the story will take place immediately post-Reaper war with Shepard as the PC is that Bioware simply does not want to keep track of all of the decisions Shepard made in the OT and try to make a nod to all of them. They had enough trouble dealing with this in ME3. It will be much easier if almost all of the people alive during the OT are dead of old age. So then the only decision Bioware will need to care about is the one with the Catalyst, because they can't avoid it. Of course, if they canonize one ending many people will cry foul, but that is the cost of setting a story in the Milky Way post war. (Personally, I'd love 4 individual games set immediately post-war exploring the outcomes of each potential choice, including IT, but I doubt that will happen.)

The other thing I would like to know is why is there a broken piece of N7 armor in the trailer? Ok, nostalgia, but really, how did it get there? It looks like the circle seen at the nape of the neck (the back of the helmet), so that could mean we're on Alchera and it's the part of the helmet not picked up by Shepard/Liara in ME2(they took the front faceplate section). At no other time did Shepard break her helmet that we know of, and we are definitely not on Earth because of the low-hanging planet/moon in the background. If Liara is climbing a Reaper, then why would there be a piece of Shepard's armor on it? Or is it the helmet of some other poor N7?

One thing I hope does not happen is for Liara to have had Shepard's child unless they were in a relationship. Yes, Liara could have secretly gotten herself knocked up during the "goodbye" in London, and she is a bit of a stalker lady, but that would be really upsetting to those of us who didn't romance her. If a granddaughter of Liara makes an appearance, I hope her ancestors are kept deliberately vague unless Liara was Shepard's LI, in which case she can be Shepard's granddaughter as well.

Sorry for the jumble of unrelated ideas.