It is not only the sensor and image quality that dictates the overall quality of a camera, particularly when all manufacturers are and will target new customers (naturally, mostly armatures). They have to deliver a overall package: easy of use, weather-seal body (and lenses, if possible), versatile ISO, quality of compatible lens etc.
I had SD-14. After using that for couple of years I moved to Canon 7D. There is no comparison in built quality and many other features between SD-14 and 7D. IQ is not that great for Foveon sensor as compared to mono-layer Bayer sensors, particularly in high resolution 7D. The other benefit I have with 7D is the accompanying software (that came with the camera) to process and edit RAW image in my computer, which was not present with Sigma software supplied with SD14. Many other accompanying software (with 7D) are also of great use and user friendly.
In my opinion, if SD1 is more than about $1200, then its market will be more restricted. Only few dedicated fans (professionals) will be tempted to buy that.
I fully support Sigma to develop a better and alternative sensor technology, to put pressure on other camera manufacturers to improve quality of their products; at the same time give customers more, affordable options to choose from.
I personally will consider going back to Sigma if I am satisfied with their over all built quality of their cameras, rather than for Foveon sensor alone.
I just noticed that Pentax also has lunched K5 with improved features (with expected price range $ 1599 with kit lens, as per Amazon).