View an electoral map of the for-now United Kingdom for yesterday's election. You are at once struck by Scotland overwhelmingly represented in parliament by members of a party with no clout, excluded from government.
The Scottish National Party represents 56 of 59 districts in Scotland, and no one anywhere else. SNP policies and prescriptions are almost exactly the opposite of those of the ruling Tories. This signals another independence referendum in the offing.
To forestall that renewed attempt at divorce, expect Cameron to propose federalism for the U.K. Scotland already has a parliament to which considerable authority has been devolved. Why shouldn't England have its own, and Wales if it so chooses, and Northern Ireland too?
Logically the resulting lash-up would look something like the U.S., with regional parliaments standing in for state legislatures. The U.K.'s national parliament would deal with nation-level issues: defense, foreign policy, immigration, perhaps the currency, and other nationwide concerns. Presumably the Queen and her heirs would continue to serve as monarch-of-the-whole.