I know that active noise cancellation is most effective when there is a fixed relationship between the location you want to reduce noise at, and the sources of noise. I like the idea of this, as the pickups for the ambient noise are built into the helmet -- that's got to be the most specific relation to the speakers (hence the operator's ears) possible.
The problem for me with this, would be my XXL long oval head shape. I presume that Sena is a European company? That might be better from my perspective than something developed in Asia......
Perfect functionality and good fit would warrant a premium price. Not in the $2K range; if the cost of this was 120% of the cost of a carbon fiber helmet, plus the cost of a premium intercom it would be marketable.
The closer the mic is to the speaker, or perhaps the ear canal, the better the cancellation can be. But it would have to be well isolated from the speaker's output to prevent it from reducing the intended sounds. I suppose one could process the intended sound such that it is filtered out of the noise input first (and maybe some companies actually do this), but that requires more processing power and may add more lag as I would expect it to use at least one more clock cycle or require a dual core chip.
I suppose one could try a set of noise cancelling ear buds. My Sony phone, when coupled to a specific Sony set of ear buds, can do noise cancelling. Its not bad. But the buds themselves are way too big to fit in my helmet. The mic is built into the back of the ear buds and have separate channels back to the phone (the phone does all the processing and eliminates the battery/processing box). It would be a fun experiment to ride around with these though. Come to think of it, I can probably run a set of NC ear buds that might fit within my helmet with my Sena. Might be worth looking into even if just for kicks. But finding them in a low profile design may be challenging.
On a side note and going back to my comment on SENA prism cameras, I had their site up for troubleshooting an issue with my 10C and looked a little further into it. Apparently, the Prism, the Prism Lite, and the Go Pro Audio pack will allow one to record audio from the Sena to the camera over Bluetooth. This will not work with the Prism tube as far as I can tell. I don't know if it can communicate both ways. My 10C provides status over the speakers when I change the state of the camera (camera on, recording, etc.). Not sure if the Prisms would do this. I doubt the GoPro system would. And all the Sena cameras are limited to 1080p and 30fps.