Next expansion I'm guessing that alot of peoples subscriptions will end cause of the fact more people this time around have pretty epics and alot of people don't want to start all over again. Also the hardcore raiders probably aren't feeling challanged anymore. Or maybe they sucked all along and the general population of wow was able to do end game all along. Who knows?
I'm guessing by 2012 they will have to start merging servers. 2013 half of Blizzard staff get fired for a crappy expansion. 2014 wow is down to 3 servers. 2015 mass suicides around the word cause wow goes offline and people are faced with real life. The end. 8)