It is just a short leap from opaque polymer receivers to clear ones. First to jump? Tennessee Arms, which published a video of their prototype receiver in action.
We can glean from the footage that the receiver is actually translucent (not clear) does indeed work and can stand up to at least 60 rounds without failure. Oh, and it is completely tacti-cool.
No word yet on pricing or availability. Their current Generation IV receivers are priced at $55.00, so I would expect this to be in that range, even with the inevitable second-kind-of-cool markup.
And yes, I want one (if only to turn it into a full-auto range toy).