Then again, if all the blue states left, the remaining country would no longer be the most powerful country.
I lived in San Diego and spent a lot of time with active duty sailors + marines down there when I attended Community College. They were from all over the country, and the vast majority were from red states. I befriended active duty military from Mississippi, Alabama, Kentucky, Texas, Oklahoma, Arizona, and South Carolina. Conversely, despite being a military city I only came across two people from California.
What I'm getting at is in the event of civil war I can't see the majority of armed forces in California supporting CalExit.