1. I could probably buy a brand new 'caveman' for less than the price of that square 56x56 sensor.
;-)
That said, I'd be surprised if the option to both see and shoot square wasn't an option on the new back.
I can shoot square on the 45MP Z7 and still end up with a 30MP file that would give 56x56 film a run for its money, and some. 2. Let's face it, it's probably all too late.
1. But Keith, you know that you wouldn't! (You'd spend it all wanderlusting.) Neither would I. For me, It's far too late to be able to produce the reflexes that speed requires. ;-(
The problem with cropping what a camera can actually give you is in the head: I'd feel I was being silly and wasteful; second-besting. Once touched with the puritanical ethic, it's indelible.
2. Probably all too late: for me, no doubt about it. At a push, not dependent on lottery but
solely on the unlikely event of work, I might stretch to a D850 and a fast 300mm. The one I had was the IFED f4.5 version and seldom saw any use. I did make a couple of scans from Kodachromes where it was used to shoot a bell in a church tower: terrible chromatic aberrations. As bad, the focus was so loose that just letting the ring go was enough to upset focus. It all vanished back into a camera store on one of my ill-fated trades to 6x7.
I bought a new plant for a pot today; felt quite good about that.
;-)