But the amount of data will also increase relative to available bandwidth. A few years ago a 2MB page would have been unthinkable. Maybe in five years we'll be seeing 10MB of resources delivered for a page load.
My parents have only upgraded to "high speed" 512kbs in the last few years. My 80 year of Grandfather is still on dial up. I don't think expecting him to wait 5 minutes to load a Tweet is reasonable.