Honestly, I like the idea of slowly immigrating people into other continents. I also like the idea of an invasion to drive characters off the continent. I think the two of them put together would make for a helluva fun event and achieve consolidation at the same time.
Have a GM invade x continent. The GM will be able to set the pace of the immigration by destroying realms (not a roflstomp, but a sense of impending doom will be evident). Once a realm is down to their capital, take the entire realm and throw characters/realm on another continent. The immigrant realm will probably have to steal land or have it created, but the whole process would be GM and players working hand and hand to freeze a continent (in case players come back) and reshape another.
