Secession of the blue cities would probably be a net positive. Most of them are huge tax drains on their host states, high cost, and also the center of all the problems with crime. Even if they have economic activity they usually produce little of real value, it is all trade and finance and a large population of useless eaters. Secession would put a lot of pressure on them to sort out our their own problems. So, great idea! Don't let the door hit you in the ass.