This gets even bigger if they throw their IP muscle behind it like they do with ICC. If you can get (for pay or free) fast matrix multiply, FFT, crypto, etc cores for the FPGA you will see even faster adoption.
If they're clever enough to make some of those IP cores available to say MATLAB adoption will be faster still.
Nothing sells hardware easier than "do no extra work but spend another couple of grand and see your application speed up significantly"
MATLAB will recognize if you've got FFTW or ATLAS or other highly tuned numerical libraries installed. And MATLAB will then use them whenever possible.
If Intel does a good enough job of providing a collection of compute kernels and the surrounding CPU libraries to make using them roughly as "easy" as CUDA then a lot of people will pick that up.
I don't have any hard numbers but I would suspect that there are a great many more people who use MATLAB on a CPU than those who do MATLAB->HDL. So what I'm speculating about is that Intel might support those folks who use MATLAB on a CPU for more general purpose things.
If they're clever enough to make some of those IP cores available to say MATLAB adoption will be faster still.
Nothing sells hardware easier than "do no extra work but spend another couple of grand and see your application speed up significantly"