Looking at all these brands and systems in the various formats and the many recent announcements in mirrorless, IMO Fuji and Sony are big winners.
In 2418, Fuji with the very compelling X-T3, the variety of other camera models and the by far largest lens selection is ahead of any other APS-C competitor.
In 3624, Sony with A7RIII, A7III and A9 and the Sony and Zeiss Loxia/Batis lens line are in camera technology and lens selection miles ahead of Canon, Nikon, Leica and the newcomers Panasonic and Sigma Foveon.
In 4433/4530, again Fuji with GFX50S, 50R and 100S (soon IBIS, full sensor phase detect AF), the enlarging lens line, the option to use many EF lenses with AF adapter, CaptureOne support and fair price level outcompetes by a large margin PhaseOne XF/50MP, Hasselblad X1D, Leica S & Pentax 645Z.
In 5440 the Fuji GFX100S might terminate the market for the H6D100 and PhaseOne XF/100MP, leaving a few customers with the very expensive XF/150MP combination and a handful specialists using the 150MP back on a tech cam.
[and of course, nearly all sensors used by the mentioned brands are from Sony]
So ... a lot of competition but very few key players.