The drawing above shows what Canon’s rival to the GH5 will look like. It is based on the form factor they introduced with the XC10 but features several ergonomic improvements and an interchangeable lens mount. The lens mount appears to support EF lenses and has a locking mechanism. However there seems to be even more going on with the lens mount than meets the eye.
In my opinion these are some of the best adapters currently on the market for Canon & Nikon glass.
They take a normal Canon or Nikon lens and turn it into a PL mount (positive locking) with no play between the mount and lens.