I would note that is also a product of demographics. If all the Democrats moved to the primary urban/metro areas in the US, then by default they forfeit control over 30 states, since the aformentioned metro areas are in a grand total of 10, maybe 15 states.
Consider how many states have less then 5 representatives. Nearly all of them that are not near another states metro area, went for the Republican Party (so in general they are large area, with minimal population).
Also consider the reality that the House of Representatives is now a tyranny of the minority (ironically).
First past the post also punishes Democrats moving to urban areas, since they increase an advantage that counts for nothing. The more wealth urban areas get (urbanization tends to do that), the less their political power they have, relatively.
In the end, the Republican party will probably end up having a strong lock on government, but the Democrat urban areas will dictate via economics to everyone else anyhow (California, New York and Texas routinely set standards that business follow and apply uniformly since it would cost too much to make different versions for the minority part of the economy, main one I'm familiar with is textbooks, but California environmental rules often come into play too).