Plenty of compilers/languages already perform autovectorization (to take advantage of SSE, for example); however, the problem in most cases is that the compiler

Plenty of compilers/languages already perform autovectorization (to take advantage of SSE, for example); however, the problem in most cases is that the compiler won't (ever) be able to determine, at compile-time, how your code is going to run, so it'll have to take the safe route and not vectorize it, or only vectorize some of it. Now, what follows is just my opinion: I think in the (relatively near) future you'll see a lot of data-crunching, high-performance code switching away from C to some of the newer functional languages, or even back to some older languages like FORTRAN -- it's easier to express certain kinds of data-parallelism in those languages, which makes less work for the developer while also making it easier for the compiler to generate optimal, vectorized code.