Your statement implies the point of FF mirrorless is to push spec barriers or to be small. Consider a different perspective.
Comparing to the 5D4...
If you don't shoot video:
Additionally, if you do shoot video:
- Your RF lenses have a control ring that you can customize, and you can make adjustments in 1/8th stop increments now
- All your EF lenses can be rear ND or CPL'd and they all get a control ring now as well
- Your mirrorless 5D4 now has Eye AF
- Your mirrorless 5D4 now has AF points all over the frame
- Your mirrorless 5D4 will (someday) be able to adapt non-Canon glass
- Your mirrorless 5D4 + adaptor ring now costs ~ $2500 (depending on which one you get)
- Your mirrorless 5D4 now has exclusive access to an industry first zoom and (possibly) Canon's first comprehensive workhorse 50 prime.
Yes, some stuff is taken away from the 5D4 experience, but so is the price.
- Your mirrorless 5D4 now has a tilty-flippy
- Your mirrorless 5D4 can now output 10 bit 4:2:2
Stop comparing to A7. Start comparing to Canon SLRs. This thing will sell very, very well.
Yep! - got it in one there!