Speaking as someone who used to use Matlab exclusively and almost got a job with the Mathworks let me say that I hope you're right. I love that scipy gives me a general programming language, and I love that it's free.
But there is one major obstacle before that happens...toolboxes. I'm in the DSP realm too and the signal processing package of scipy just doesn't hold a candle to all the numerous toolboxes that you can get with Matlab. There are some BASIC functions that are missing from scipy and there are a TON of extra functions in the Matlab toolboxes that aren't anywhere close to being implemented in scipy. The communications toolbox alone has so much that scipy doesn't offer it's not even funny.
I guess I should stop complaining and start contributing. But I honestly don't know that I'm good enough of a programmer to feel like I could contribute something. I guess I'm pretty sure I could implement a few algorithms without major bugs, so maybe I should pitch in. I don't know that it would be the prettiest or most optimal, but you've got to start somewhere.