I think each camera caters to a different portion of the same market. On paper, the Sony seems far superior. No offence to Sony fans, but In real life, I'm not a fan. I obviously haven't used the RX1R II yet but I have used the RX1R. Standard faire for Sony. IQ is great but UI is a mess. For me, user experience is very important and Sony just doesn't have what I'm looking for. I also am not a fan of Sony as a company. Denial of real issues like overheating (NEX7 and rumors of the same with the A7RII), ongoing requests to revamp the UI being ignored, expensive product being outdated on a 6 month +/- product rotation (I know it's the nature of the beast) etc. have made Sony a "no buy" for me.
While the Leica Q is not perfect, nor is Leica as a company, I think the user experience is far better. Leica, you get it, or you don't. Jewelry or a precision photographic instrument? One could also say buying a Leica could be more of an "emotional" purchase. Not to say that the Q isn't technically advanced...It is. It really is a very different experience from the Sony.
So, is the Sony a Q killer? I don't think so. I don't think that those who really are really intrigued by (and can afford) the Leica will move to the Sony. For some, the Q just doesn't make sense.
There is definitely room for both.
Just my opinion...
P.S. Picking up my Q today...