I'm an old electronic technician, who has seen the progress from tubes, to transistor, to IC , to the ultra-miniaturized cmos largescale integrated circuitry we see today. The limits that are mentioned on just the limits in the "limited technological view" of the writer. New technologies are always emerging. Some of the things I see.... whole SMP systems (including motherboard ) all in a single water-cooled chip, with optical laser ports for I/O.

For years I have believed that ultimately, our computing will switch from controlling electons to controlling photons,... yes, computers that run on light. See All-optical control of light on a silicon chip But that is probably even a limited view, how about controlling shifting quarks, or string vibrations. It will come if the human race dosn't self-destruct.

There have been all sorts of articles on laying down diamond film substrates for ic chips which will be almost immune to heat, and its proposed use in all sorts of things. Do a google search for "diamond substrate cpu". There is a link to an article about an 8000 Ghz cpu !!

As far as concurrency of software goes, it will happen. Most of the popular languages now, have a goal of running other languages Inline. Perl6 is striving for that.

It will take a generation of "fresh minds" to step back from the "language wars", and say "gee...we could make this one "uber-language" that can run anything else inline, and the processers will be so fast that speed will not be a concern except in some reseach/military applications.