Well, this is a little bit of crystal-ball stuff, but I believe the future is in networking.
The internet is still in its infancy. The move from electrical networks to optical networks, and new technologies like optical switching, make this a field with room to grow.
The demand for bandwidth is not falling. Look at the popularity of cable modems. People want more complex information, real-time video, etc. Remember that for decades, people have been dreaming about real-time virtual reality, television on demand, and so on. We don't yet have the bandwidth, but we're only a few orders of magnitude away.
One of the challenges with optical networks is the interface between the extremely fast fiber and the much slower wire. Optical computing is a ways off, in large part because nobody has a practical way of storing the state of an optical signal.
The other fields, like applications, servers, etc. will still be there, but networking is where the most significant growth willbe. If I was starting over, this is probably where I would begin.