Notch recently commented on the perception of Endermen as they currently exist, saying "they're annoying, and because I nerfed them and made them too easy. I shall fix this." Any number of changes could be made to the Endermen to make them more difficult - more health, higher damage, more aggressive behavior - time will ultimately reveal any changes made to them.
Endermen have been a popular topic since their introduction in the 1.8 update, starring in numerous videos that run the spectrum from hilarious to terrifying. They have certainly set themselves up to be as well known (if not more well known) than Minecraft's ever-popular Creeper. What changes await this elusive monster? We will find out soon!