Huh? Seems like too narrow a focus on size. Larger lensmount probably equates to larger lens elements thus more expensive glass and heavier, bulkier lenses. The drawing may be second to none, but i'm not sure that's what people were looking to gain from mirrorless.
Well, no... It is possible to design small lenses fitting a large mount, but the opposite isn’t true. Or at least is much more difficult and may end up resulting in more bulky designs.
Besides, there are various reasons for the interest of people for mirrorless, but those have been strongly shapped/limited till date by the design choices made by Sony whose strategy accross sensor sizes was simple: design the smallest possible body around each sensor size.
Leica has chosen another route but is obviously a niche offering.
So when investing in a strategic mirrorless mount, I will consider its size as a very important decision criteria. Not because it is Nikon coming up with a large one, because it just makes sense.
Cheers,
Bernard