This is obviously aimed at the Leica/Ricoh crowd, not high throughput photography (events, sports, documentary) or product. Also, 4300 raw files should be enough for quite a long holiday/many street photography sessions.
Maybe kinda? As a Leica owner myself, honestly I like my traditional controls and wouldn't trade my camera for the Sigma BF.
This feels more like the Tesla Roadster, which I guess some would say is meant to appeal to sports car fans, but I think honestly tries to create a new market. The old-school sports car guys who enjoy revving an engine and shifting gears aren't really the market for a Tesla Roader, it's a new generation of people who are enthusiastic about electric cars.
I think this is trying to do something similar - creating a new market for well-off Gen Zers whose parents didn't even expose them to traditional cameras growing up, just smartphones. People for whom those cryptic old control knobs hold no appeal. "Here's a powerful camera with a much better sensor and lens than your phone, but you don't need to be a camera nerd" is more what I imagine the pitch to be.
No-one who shoots M-mount at this point is giving up their rangefinder for an LCD-only camera with no viewfinder.
Those people won't have issues paying that amount.
GR III = ultra-compact, fixed focal length, $1000, poor autofocus
Sigma BF = compact, interchangeable lens, $2000 + lenses, ??? autofocus
Leica Q3 = compact, fixed focal length, $6000, reliable autofocus
These cameras are loved by street photographers, casual landscape photographers, documentary / environmental portrait photographers, and there's a significant Japanese lifestyle photography scene ... I often wonder if Sigma has this market in mind, which is not so visible if you're not in Japan or don't know where to look on Instagram (dig into the #sigmafp / #sigmafpl tag and look for washed out / blue-tinted photos of flowers/nature, for instance).
The major downside is no stabilization, which will severely limit the shooting envelope compared to these other cameras. I shot with a Sigma FP for awhile and the combination of poor autofocus, no stabilization, no viewfinder, and it still being heavy compared to, say, a Fujifilm camera, made for a very limiting experience. This will, however, be a user-experience upgrade for people who are happy with FP (which, honestly, I still miss sometimes).