Then again, we have seen two rather traditional takes on supposed Romulan starships - a classic TOS style vessel and a winged design resembling an anorectic Klingon BoP. Neither of those was shown attacking anything identifiable as Starfleet or Federation, although the latter was shown approaching Mars in... an armada.
Instead, an all-new design distinctly steering away from the curved lines of the above was the attacker amidst those red clouds. Perhaps SF or UFP suffers the consequences of standing up for the Romulans - but the armada part is unrelated to any combat, and indeed only was involved in the rescue of the Romulans from the (natural?) disaster of homeworld loss.
That there are Romulans messing about in a Borg Cube does not necessarily make Romulans the antagonists of Picard. There are humans doing the same, after all, and we even get bilingual signs at a facility dealing with assimilation. Possibly it's a joint Romulan/UPF project related to those androids also shown, and the project is the thing Picard will have to fight.
The one thing of note is that at least two Romulan characters in the first trailer, the female narrator and the male visitor to the vineyard, think Picard is one of them, a staunch ally and savior. Him fighting the Romulans doesn't fit that picture too well; by extension, him quietly retiring to his home on Earth doesn't fit the picture or Romulans fighting Earth much.
Timo Saloniemi