You could also turn on foreign leaders you are harbouring, and turn over to the enemy(covertly). I think that exiled leadership should only last for 40 turns or so. It would be long enough that powers coudl try to regain the lost territory, or at least some of it.
Satellite States -
Whenever you conquer new territory, locals will resent being controlled by a foreign power. You will have the option of establishing a Puppet State. This puppet state is a friendly variant of the civ who used to own the territory. This means that the locals will be much happier, and you continue to generate culture and retain the culture you had. Think of the Vichy French during WWII. The master of the satellite state would have military plans each turn, free info on all ciites, and one-way-ROP. Satellite states can eventually try to become independent, but usually needs international support. Master states will usually maintain a military presence. These states also count towards the territory and population requirements of Domination victory.
UN Nation Building -
One function of the UN can be to grant sovergnty back to a civ that no longer maintains soveirgnty. This is civs that were defeated and conquered(not satellites, no surviving governments). Any city that has nationals of the dead civ can be returned to the revived government. A proclomation is drawn up by the 3 to 5 most powerful memebers. less powerful members coudl try to buy votes for certain cities to go one way or the other. Negotiations go on for up to 10 rounds of suggested changes. Whenever the members of the council can unanimously agree on the fate of 80% of the contested cities, the contested cities fates are determined by majority vote. IN the event of further tie, the general assembly votes on the city. Once the document is drawn up, the general assembly votes yea or nay on the proclamation, and the Security Council does not vote here. If it passes, nations have 2 turns to move troops out of the soverign territory of the new nation.
The strategic implications may be to severely weaken an empire(imagine Kurdistan, which would take up 1/3 of Turkey), Create a strategic ally(Israel), or eliminate someone's monopoly on a resource.