My wish list:
(1) DCC ready two-Rail versions of ALCO-GE S-1, S-2
(2) DCC-ready two-rail versions of ALCO-GE HH-660
(3) DCC-ready two- rail versions of ALCO-GE RS-2
Having seen the modular set-up at the 2021 National O Scale Convention at Denver, I believe that the area most likely to provide future growth in broad-gauge two-rail railroading comprises switching and shelf layouts, either bolted to the walls or done up in something like HO guy David Barrow's "Domino" modular system. This is not to slam people with basements, attics, "mother-in-law" spaces above their garages, or spare buildings, but a lot of model railroaders live in places with concrete slab foundations. just above bare rock.
I admit that my choices for early first-generation switchers may seem annoying for O scale modelers doing later eras. On the other hand, some of the early ALCO S-series switchers had incredibly long lives as industrial locomotives, outlasting cab units and contemporary steam locomotives for as long or longer than half a century.