Right, as Bitcoins are lost, the rest of them will gain in value and therefore can be divided in smaller and smaller increments.
So even if 20,999,999 become lost, the last 1 BTC will still be enough to run the whole economy.
(And then I'll be rich, because I just happen to find some of my lost coins).
It won't be. That's 1 billion units left. if there's 100 million bitcoin users, assuming wealth was perfectly spread, they could only have 10 units each. If 10 units is their life savings, there wouldn't be a denomination small enough to buy a candy bar.