Digital 5" x 4" Inch Back For Large Format Cameras

I just read this article about Canon making a 202 x 205mm digital sensor.

http://www.dpreview.com/news/2010/8/31/canonlargestsensor

It's old news now (31.8.2010), but it made we wonder how long it may be before a 5x4" digital back might be made for large format cameras ?

I know chip cost has always been a deciding factor, but surely larger chips are much cheaper to manufacture now.

A 5x4" digital back could work much like a Polaroid back and just slip in and out of the camera after focusing etc. A 5x4" touch lcd screen wouldn't be that hard to make either.

The quality of the chip would not even need to be the same standard as existing smaller chips so would be cheaper to manufacture.

Just wondered what thoughts people had on the idea ... would give a whole new lease of life to all those large format cameras on ebay !