I was just about to post something about this. While I wouldn't say it's obviously Romulus, it sure the hell looks like Romulus and the impending supernova.What we see in the teaser is obvioulsy the destruction of Romulus ... I wonder if the series will actually deal with that. The disappearance of a major player in this quadrant might have very interesting consequences. It would certainly be in line with Nick Meyer's comment about TUC as a reference.
And we could have guest appearances by pretty much anyone from the TNG era!