I have conflicting feelings about this. The low-level programmer is disappearing because the abstraction layers are getting better, which means the complexity we deal in is "how do I get a 30 machine cluster to map-reduce efficiently" instead of "how do I optimize these instructions so I don't blow out my L1 cache".

But...all abstractions in computing are leaky, and not having an understanding of lower levels of abstraction will come back to bite you.

The simplest example is floating point: how many pennies have been mis-appropriated because a developer used a float instead of a fixed-decimal number. If you understand how the underlying floating point abstraction leaks, you would never use an IEEE float for anything requiring exact decimal values; if not, you feel comfortable using the native type that has the ability to represent decimal values. You don't need to actually know how the float is represented to achieve that.

The real trick is understand how much of each layer of abstraction you need to know. A generalist needs to know enough about computer architecure, the network stack, security, etc., that he knows when he either needs to consult an expert (Google often counts ;) or when he is ok to rely on that abstraction, but if you try to learn too much, well, you aren't a generalist anymore.

Great generalists are, by definition, great at figuring that out. As a result, they are incredibly valuable because they are really good at just getting stuff done.