The Monkeysphere Theory is a perfect example of why I think instancing doesn't take away the Massive aspect of MMOG's. Your Monkeysphere can only be so big.
My Monkeysphere in an MMO is probably about 10 people. That's pretty much my guild give or take a few I don't ever see and a few outsiders. The rest of the people in the game could die in violent car wrecks and my life would flow on normally. MMOs don't really count as a good base for that theory I think. Frankly, even if those 10 people bit the dust, I lack that tactile knowledge of them to ever really be emotionally attached. I'd probably just quit the game.