Oh man! Now you've done it.
My Rans Rocket has 20" wheels and is my Katy Trail bike. The Katy is flat but I have to climb a significant hill to get from the trail home so a low-ish gear is a must. Also, since most of my riding is on the trail, there are no steel belted radial wires so fewer flat tires to contend with. The Rohloff hub however, even if I can get one at wholesale cost, would roughly triple my investment in that bike. Vertical dropouts too so I'd have that to contend with.
Don't think that it's going to happen.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.