Time only will be the final judge, but if the past is any indication, with the quenching of realms like Viridian, Melodia, Virovene, Raivan Empire, Aquilegia, Myern, Tulsoma, Ordenstaat, due to reasons both due to man and nature, then there is not a very promising future for the current small realms. Their military strength is negligible, and would require the assistance of strong military to keep them alive for any amount of time. I expect that Barca has been enjoying consistent aid from Terran or D'Hara. Aurvandil fighting Madina is a rather bad sign for both of them, but that's human conflict for you.
My big assumption here is that there are too many egos trying to strike out their own names, but in the process that only spreads resources, and leads to the perpetuation of Dwilight as mostly concentrated in only certain areas. While the stories that could arise from it are great, it would be a constant frustration for those who sought fame and glory. Well, perhaps fighting monsters does earn some "glory".
Many of the realms you mentioned were isolated. This is no longer the case, with D'Hara and Terran having a solid border with each other and at least a handful of stabilized regions each. D'Hara hasn't had any rogue problems since the "Event" that, combined with massive starvation and invading forces, led us to lose most of our regions. Rebuilding efforts since have been going great, and our trade is much more developed then it was then. Though our military is rather weak, and our omnipresent walls are our greatest asset (only 1 region can't have them right now, out of the total 2 at our peak of expansion).
Ordenstaat is another story. There was lots of multicheating, which lead to rebellions, which led to them being mistrusted by the neighbors at best, and despised by many. While Barca has the full support of her neighbours, such could not be said of Ordenstaat.
Terran and D'Hara have been there for a very long time, and there's nothing to hint they won't remain for long still.
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