Originally Posted by
Hanginon
Nikon's newest glass with internal motors can be used (with an adapter) on Z's and Sony's.
Canon EF glass can be used (with an adapter) on R's and Sony's
Panasonic is also rumored to have a FF mirror less coming, and I bet it will be able to use other brands glass (with an adapter), just like Sony.
The world is moving towards "no moving parts" - a camera body that is really just a computer tied to an imaging sensor - and in theory (if the firmware is coded properly) should be able to use any lens that has it's own focusing mechanism (with the appropriate adapter).
It will be like the FF version of micro 4/3's, and IMHO long term will kill off APS-C and DX. Fuji is smart staying out of it.