I also believe that. I got happy and upset at the same time when I recognized Liara, but then was told that they showed andromeda and an ark, and I was like "Wow, it's gonna be the sequel to ANDROMEDA but with a cameo of the Milky Way".
Doesn't matter what choices you make in the trilogy, Liara always lives. So here are my fan theories about how this could be possible:
- Destroy ending: Liara obviously lived, and a hundred years later the people of Andromeda manage to contact her. Doesn't matter whether Shepard lived or died (depending on EMS).
- Refuse ending: Everyone was doomed. We got to see Liara's message in Andromeda, but that doesn't necessarily means everyone died in the MW. Even Javik said he was born when the reapers had already attacked in his cycle, yet some protheans got to escape and preserve theirselves in pods. Liara always becomes the shadowbroker with great resources, I struggle to believe she wouldn't have thought of a plan to preserve someone or even herself to have better chances to warn the next cycle.
- Synthesis: She's still alive for obvious reasons. Maybe the weird green glow disappears eventually?
Also, I'm hopeful that just the same way we (hilariously) got to play joker on ME2 without seeing it coming, another excuse of Liara's presence is that we could play as her
It could also be that the trailer is for a game that is between Me:A 1 and Me:A 2, like it happened with Captain Spirit (It wasn't Life is Strange 2, just a game in the same Universe that happens between Life is Strange 1 and Life is Strange 2).
Personally I'll still solemnly believe the trailer is for Andromeda 2 until Bioware directly and officially denies it. They still have so much to work with, Andromeda is as good and as filled with mystery as Mass Effect 1 was in its day, and hell, I'm still waiting for them to discover the kett are actually evolved prothean (another personal theory and wish of mine)