As DSLR sales continue to plummet, reports out of Japan are that Canon is developing a Mirrorless-to-DSLR ‘Converter’ for the EOS R mirrorless cameras.
A report published in Nikkan Kogyo Shimbun, suggests Canon is working on some sort of converter that can transform a mirrorless camera into a DSLR:
“We are also developing a converter that can join a mirrorless camera to an interchangeable lens for a single lens reflex camera.”
While this could describe an EF-R lens adapter, those already exist. Canon Rumors points out that Canon filed a patent in January of 2018 for a mirror-box/mount/OVF attachment that might attach to a mirrorless camera.
I’m not sure of the value of such a device unless Canon’s plan is to eventually get rid of their DSLR lineup without totally abandoning that user base.