Is a mirrorless camera really going to be smaller? Fact or Fiction?

In general yes, at least the camera body in most cases is going to be much smaller than a traditional DSLR would. But when you factor in the lens that is required to attach to the camera body size will for the most part be the same as a DSLR.

The size of a lens is not going to be based on whether its for a mirrorless or DSLR camera but rather Physics. A great example of this is the Canon RF 85mm f/1.2L USM and the RF 50mm f/1.2L USM. These are great lens’s in the respect that the image quality is top of the line. But there are drawbacks. First they are heavy lens’s each over 2 lbs. Then there is no IS (image stabilization) in the lens. Considering that the Canon EOS R body has no IBIS (in body image stabilization) its going to be hard to take sharp photos hand held.

Going back to topic. For Canon to achieve the quality of these two lens’s size had to take a back seat to physics. The glass and size of lens required to get max aperture of f/1.2 can’t be done in a more compact form factor.

But all things considered mirrorless is where the technology is going and like the film camera its only a matter of time that DSLR cameras are going to be a museum piece.