Who says that the four nations of EVE need to be the arch-nemesis' of each other? If I had to pick an arch-nemesis for the Empire it'd be the Sani-Sabik cults, if it weren't for their lack of organization, or maybe better Sansha. After all is said and done, the four nations aren't that different, really, if you compare them with the factions that didn't sign the CONCORD charter.
I think it's one of the big ailments of the EVE community that they have to think, apparently, that within the four nations there must be the 'big struggle' and that this is oftentimes thought of as a struggle of 'good versus evil'. (And I think this perception is shaped by the players society: In my experience Americans tend to see these polar opposites as a necessity, while Europeans do less so: Maybe the European Union did deserve that noble prize after all, the post-war reconciliation of France and Germany seems to have achieved something.)
Nations don't need arch-rivals to whom they are opposed eternally and locked with into a struggle that is about all or nothing, save for their propaganda. That's why a senator will say such a thing. It's not because the Empire is really the Federations arch-nemesis: It's to keep his voters in line. Fear is a strong ally in the struggle to get re-elected.
So, as I said, the tendency to paint any two factions as polar opposites that by necessity need to exterminate another eventually is just oversimplification of the situation, imho. It's even more simplistic than the picture CCP is already painting.