Oh, sure, you'll still be ambulatory. You'll walk (for a while, at least), talk (for a while at least), wine, and dine (when eating goes, you're in trouble). But the world you labored so mightily, in childhood, in young adulthood, to apprehend, begins, piecemeal, to slip away.
NPR runs an occasional segment on endangered sounds. Recently, they featured that ubiquitous squawk/buzz of my youth, the sound of a modem connecting. To me, the sound -twangy with an underlay of steel- conjures afternoons hunched at the computer typing mad and terrible poetry, evenings yelling at my parents to get off the phone so I could check to see if my crush had written me back in the last three minutes (no).
It wasn't a particularly enjoyable world, but it was mine, and it's gone.
Encyclopedias: kaput. I found a set by my bed a few weeks ago during my travels and was startled to be reminded of their browsable heft. We've gained Wikipedia, but we've lost serendipity: no longer do you flip to leprechauns and come out with leprosy.
The trick is, you don't notice it happening. One minute you're staring at skeletons in volume S and the next moment you're an adult. Car phones, phone trees, pagers, walkmen, card catalogs, summer jobs: poof!
But what else is new?
It's worth taking the question literally; what's new is all you'll have, in the end.