There will be no threat to Leica. I don't think there are many people who by a Leica because it is a particularly useful camera, they buy it because it is a Leica and all that entails.
Lets face it, the Leica's have a history of really being built to last. I'm not sure about the latest crop digital cameras, but we can certainly say this about the older film cameras.
I get great pleasure of taking my 50+ year old Leica M2, for a walk, knowing it still functions perfectly after all these years.
As nice and useful as that little Sony is, I doubt it will be much use in 50 years. It likely won't be much of an heirloom.....but my M2, in another 50 years.....who knows?