The EOS C50 of my dreams has the same sensor as EOS C100 with M mount and few M cine lenses.
With a price around 3000$
I don't think that would work. The C100 sensor is 24.6mm wide x 13.8mm high (Super 35). The M mount only handles 22.5mm wide x 15.0mm high. They're close though. What I find interesting about the M mount is that it has one more contact that EF mount. My guess/wish is that it is for power zoom controlled/monitored by the camera.
The PL mount and Super 35 sensor size seems to be popular partly because there are a large number of high quality, expensive and apparently highly prized legacy PL cine lenses.
I want something incorporating the best features of both the XF100/105/300/305 camcorders and the 5D3 still camera except with an M mount, an assortment of dedicated video lenses and something like the Metabones speed booster/adapter so that I can still use my EF still lenses and gain 1 (or 1-1/3) stops while I'm using them.