Think of Star Trek Online
. The game and its Path to 2409
and The Needs of the Many
tie-ins deal extensively with the Post-Romulus era.
Here, several colonies vie for becoming the next capital. Taris becomes praetor, the captial Roma Nova is built on Rator III. When Sela becomes Empress in 2408, the Empire is finally politically stabilised.
That is, until she is abducted by the Iconians in 2409. The political order falls apart again, the Tal Shiar attempts to exterminate the Reman species (which is still part of the RSE in the STO continuity). The Reman rebellion, led by Obisek and based in The Vault (cf. ST: Nero
) ally with the Romulan Reunification Movement led by D'tan.
Together, they settle a new planet called New Romulus in the Azure sector, intent on changing the deceitful ways of the Romulan people. They are on good terms with the UFP and the Klingon Empire but harassed by the Tal Shiar and the Tholian Assembly.
The end of Romulus is not the end of the Romulans. Either they become crazed fanatics (like Nero) or join forces with their Vulcan siblings. After all, it's about time the UFP swallows another major former enemy for optimism's sake.