Matt Kohut from Lenovo blames LCD makers. He says they make much more profit selling panels for TVs than for laptops, so they standardized on HDTV aspect ratios and won't supply affordable 4:3 panels:

http://lenovoblogs.com/insidethebox/?p=220

(I have no idea how accurate this is, but other computer makers have given similar explanations.)

I'd believe that if anyone was actually selling 4:3 laptops at a premium.

That wouldn't have happened yet. In my head, I have a loose projection of when I figure it would, it's something like 2013-2015

In any case, I'm not saying it's fact, just loose speculation

I don't think waiting until people decide they can tolerate 16:10 or 16:9 would be a good strategy. Thinkpads were some of the last laptops to offer 4:3 models, and people were buying them for that reason. They already have premium prices and a reputation for quality; I think if anybody was going to do this, Lenovo would already be doing it.

These are people who don't understand that marketing is important, despite the obvious example of Apple who seem to not only survive, but thrive almost purely on marketing...

I suspect the truth is more likely that 16:9/10 is so much more popular that its no longer economical to produce 4:3 laptops.