Probably the biggest worry with GPU-enhanced anything is with how imprecise the cores are.
There are a lot of CUDA cores on an nVidia GPU, which means a lot of power, but they are manufactured with fairly high tolerances. The end result is that you will more often than not get a non-deterministic result for any given floating point calculation, and this lack of precision in consumer GPUs is why video game AI path-finding is still done on the CPU and why decent professional workstation GPUs cost thousands.
Graphically demanding entertainment software doesn’t need precision, just power. It’s easy to forgive some inverted colors on a texture or a polygon with slightly wonky coordinates for the few milliseconds they appear and are later re-drawn with fewer noticeable errors, but it’s not easy to forgive the same on a few milliseconds of frames rendered for a special effects in film or, in the case of audio, your reverb taking on a different character for a few milliseconds every once in a while on playback.
Results quality-checking and garbage handling on the GPU is still fairly inefficient, so there might not be any performance gains to be had when all is said and done. I think if you want more DSP power, just buying a machine with a faster CPU (or more than one fast CPU) would be a better investment than a mega-GPU at a fraction of the cost with the hopes it will be made more useful later. By the time any developers get around to justifying off-loading vital floating point work to the GPU, your current one might not let you benefit from it.