Read “Secession Made Easy,” which addresses inter-State secession, that is, the annexation of a portion of one State by another State. Then consider the table below. It includes some moves not mentioned in the earlier post, and assesses the potential gains accruing to the GOP if parts of some States were shifted to neighboring States.
The baseline is the current lineup of U.S. Senate seats, governorships, and State legislatures. The potentially big gains for the GOP are found in the Senate. Those gains would be worth the (possible) loss of a single governorship, because the addition of nine GOP Senate seats would shift control of Congress to the GOP. (This assumes that the House remains indefinitely under GOP control for some years to come, which may be a heroic assumption.) Further, the GOP would continue to control about 3/5 of State legislatures — a big advantage when it comes to congressional redistricting.
In any event, some denizens of Blue States would become citizens of Red States — a prize in itself.