Devolution of power is a solution to the polarisation. The division in the country is real and deep and in some places inconsolable, rather than just a media mirage. Rather than increasingly violent competition for the presidential office or the federal government, a more flexible union is probably a sane idea.

The US faces no threat of being conquered, it has the most powerful military and intelligence capacity in the world by a healthy margin. Insofar as foreign interference creates division, it's precisely the lack of decentralisation that makes these attacks dangerous.