If you want to know where DGPS might be headed, take a look at your hand, because soon DGPS may be able to resolve positions that are no farther apart than the width of your little finger.
Imagine the possibilities. Automatic construction equipment could translate CAD drawings into finished roads without any manual measurements. Self-guided cars could take you across town while you quietly read in the back seat.
To understand how this kind of GPS is being developed you need to understand a little about GPS signals. If two receivers are fairly close to each other, say within a few hundred kilometers, the signals that reach both of them will have traveled through virtually the same slice of atmosphere, and so will have virtually the same line.