there’s no single cultural identity that unifies the people in the east coast megapolis besides being american and they don’t even vote the same way now so they can’t even agree on what that means today; unlike the californians.

but yes, they would dominate if you figure out how to socially glue them together somehow. the california megapolis, on the other hand, already have those things that suggests a strong cultural identity to such a degree that they have a collective nickname for californians who don’t tow the groupthink line: “little texas”. (the nickname is so pervasive that several past governors had used it). in the case of balkinization; the california megapolis is already primed and ready to go it alone whereas you’ll need time, effort and patience to create acela-stan and you also have to hope that none of the other countries somehow don’t interfere for generations while that’s happening. history proves that rich countries always interfere and neuva york alone will both be significantly richer during balkanization and already has a stronger cohesive cultural identity than that of the rest of the east coast megapolis. i would expect they will take efforts to make sure acela-stan never comes into existence as history has also proven that rich countries always do when faced w potential competition.