I am reminded of the Allis Chalmers 5020 attempted rebuild.
I found, after daily calls for more than a week, NOS pistons, rings, rod and main bearings coming from four different states, and I never did find over-sized liners which would have to be machined from liner stock. The costs associated with parts, freight, machine shop and delivery were too prohibitive for the AC 5020 owner to finish the overhaul.
Recently sold my Massey Ferguson 1020 (early 90's model) for the same reason. The Hinomoto, then Toyosha parts support from AGCO became less every visit to their parts counter.
Now John Deere...some 14 Yanmar based JD models will be as you've stated above, the end of another contract built tractor, parts and support issues will be gone in just a few short years...
Mark