Let's agree that 10 years from now the United States will be divided geographically into two separate nations -- U.S. Red and U.S. Blue. The boundaries will be established by the electoral votes cast in the 2004 election (States voting for Bush will be U.S. Red and States voting for Kerry will be U.S. Blue).
If you want to live in U.S. Red (or Blue) and you currently live in a Blue (Red) State, you'll have 10 years in which to migrate. All the transition details (new constitutions, terms of trade, defense treaties, etc.) can be worked out. Let's go for it.