I've only worked for a few companies, but when I was hired as a full time employee, there was no expectation I'd be doing the same job forever. If anything, there was an expectation that I'd grow in role and responsibility.
Now, being a contractor is different--in that case you typically are hired to perform specific duties, and if the duties change, the contract should be updated to reflect that.
Some of the other issues I can see from following Rick's approach): * short termism, especially as you get to the end of your working period * loss of good people as they move on after you fire them * workforce ridigity ("I wasn't hired for that")
In short, I appreciate the provocative nature of the post, but see some real fundamental problems in his solution.