Would an Ultra Wide Angle prime be a good idea? Panasonic 6mm UWA?

Just thinking here...

I love the 7-14mm panasonic, but I do find I use it at 7mm most of the time. Especially now with the 12-35mm covering the 12-14mm range, I wonder how much I need a UWA zoom? And looking at my cute 8mm fisheye, thinking what would an UWA prime be like instead, especially if it was extreme (7mm, 6.5mm, or even 6mm)?

Does anyone think that is a good idea? Would they make it?

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