Upload & Sell: Off
We would probably feel different if the FF mirrorless was $3000 and a premium cost for a brand new series of short-flange FF lenses. Granted, it would be cheaper than Leica, . . . probably. But if we get what we want, I'd think it would undoubtedly be beyond the quality level of the 6D.
So, if we get our wish for Canon to build a FF mirrorless system, and it comes in costing nearly as much as the 5D3, we might not be quite so enthused. Right?
For the cost of a 5D3, that FF mirrorless better be one damn good body, but I don't think it would be that expensive.
See how that Sony full frame RX-1 comes with a list price of $2800, but that's because it comes with a fixed Zeiss lens. Take the lens away and the price should be similar with the 6D, if not lower.
I also don't see what Canon could possibly offer in a FF mirrorless that would make it worth as much as the 5D3. Remember, Canon is very smart, if somewhat ruthless, with their product differentiation.