Paul Galburt - K2AYZ
With regard to the demise of RS-232, it's important to remember that these same UARTS support RS-422 and RS-485 multi-drop. These protocols are still in wide use (particularly RS-485) in industrial settings because of robustness, simplicity and economy as compared with (for example) Ethernet in the same setting. USB is strictly point-to-point and, while offering good bandwidth, is greatly distance limited compared with 422/485.
USB is also generally lacking the fully isolated solutions that are often required between "unfriendly" components.
For example, if you want to control something slightly smart up on a tower 500 ft away, isolated and slew rate limited RS-422 is the way to go. USB won't work and copper Ethernet's distance limit rules it out.. Fiber would be nice but gets pricy and complex - and you still likely need power wires.
In short, while most common applications of RS-232 can be replaced by USB (as long as you have some real smarts at both ends), the RS-422/485 applications are still out of reach.
Just my opinions, of course.