The Romulans, instead of automatically getting Federation citizenship, would have the option to apply after five years.
I am not sure that we can judge whether the Federation lived up to these promises. If Vashti is a Federation world, the Federation seems to have retreated. Security is provided not by Starfleet but by the Fenris group? Warlords are roaming freely with old Birds of Prey, fighting battles in low planetary orbit? The Federation seems to have retreated wholesale from the sector. Everyone might have gotten Federation citizenship, but it seems as if that does not mean much.
China's warlord era comes to mind, but this spillover makes what is happening in Romulan space worse. It is as if Chinese warlordism led to the abandonment of Hong Kong and Vladivostok. The Federation is retreating in the face of deep instability in Romulan spaces.
(How ironic, then, that the border worlds which threatened secession find themselves so directly exposed!)
I'm not fully convinced we can look at Vashti's political situation as evidence of "Federation retreat" since I don't think it's yet clear that Vashti is claimed by the Federation as its territory. But yeah, the Federation has certainly taken an at-least somewhat isolationist stance post-Mars/supernova, and that works really well as a commentary on both Trumpism and Brexit (one of the stated intents of the show).