I tried the Leica S (007) once at the Photokina but focus accuracy with the S 100f2 was mediocre and they told me that the S system does not have auto focus micro adjustment, so this already reduced my interest in the system. Another reason is my experience with reliability of Leica products: All my Leica M components had to see Leica service (Leica M9 for sensor exchange and focus adjustment, M50f1.4 asph. FLE for focus precision adjustment and focus ring too tight, M75f2 asph. FLE for focus precision adjustment and didn't reach infinity). Then if you read the nightmare reports in the Leica S forums (sensor cracks, sensor corrosion, af failure, electronics issues ...) plus no S camera or lens announcements since several years and considering the Leica boutique prices you are wondering what kind of policy Leica is following.
Since the arrival of the Fuji GFX and Hasselbald 1XD systems, Leica is no longer alone in the crop MF universe. I use the Fuji GFX since day one of market release, now with the 23/ 45/ 63/ 110 lenses, plus I have extended experience with the Fuji X series using X-E1/ X-E2/ X-T1/ X-T2 cams and a variety of X series prime and zoom lenses over the years and all I can say is: Fuji products are extremely reliable (plus very frequent firmware updates that remove bugs and add functions or improve af speed and accuracy), I didn't have a single failure with any Fuji product and the GFX and the four primes surpass image quality any system I ever had: the Fuji version of the Sony sensor - even released 2014 - is visibly better (color accuracy, skin tones, 'pop', dynamic range/shadow recovery, sharpness due to small micro lenses) than the sensors of the Sony A7RII and the IQ180 and the GF primes are all on Otus level. I love the manual operation of the camera, the tiltable screen is very useful for candid shots (camera at waist level with screen tilted upwards) as well as for architecture shots by hand (camera position above head level with screen tilted downwards to reduce keystone), the many outside-center focus points and the face/eye detection AF function are such a help for portrait shots, all these features the Leica S does not provide.
100 MP, quicker phase-detect AF with even more focus points, an EVF with possibly higher resolution or at least reduced black-out time and higher refresh rate can be expected to come on the market within 2019 in the next camera body generation, the GF 250f4 plus 1.4x extender soon will add a tele lens, with the Steel Canon EF and Contax 645 AF adapters I can use my TSE lenses and Sigma Art lenses for very shallow DOF and the C645 lenses with auto-focus, this package and the perspective makes the investment into the GFX ecosystem very reasonable, also considering the rather moderate price level of the GFX components compared to the comparable Leica and Hasselblad offers.
IMO other than the absolute preference of an OVF camera and the 'look' of the S 006 Kodak CCD sensor I see little reason to invest in the S system.