Language keywords versioning approach

Java 1.5 again made it necessary to review code and prefix classnames that Java appropriated, and we had for years. This is a repeating process and it is not too bad, although it can annoy the hell out of me when I was planning to do other things. The principle here should be, who was first for this particular source file. The import mechanism should account for this problem, and also the set of keywords for the language should not be fixed, so that if I chose to use something that later became a keyword, my choice is what counts. We are not talking about perl, php and vb, that just change the whole language and let the users suffer or go bankrupt through it. No, we are talking serious languages like Java, that should have more support for this than language level switches on the compiler.