I'll admit I don't think I've ever looked seriously at Internal Geared Hubs. But one idea I can't believe got put down on this site is direct mount caliper brakes. Maybe they came about around the time disc brakes already emerged but the idea I thought would be cool for large tires. I still believe in 27.5x2.15" tires though (even 2.35"). One of the reasons I believe the 650b fad is not as hot though is because companies like Brodie Bikes eliminated some of those models and replaced them with 700c models. So I guess since 700x40c has caught on I hope one company will come out with direct mount brakes for those.
As a passing comment on tires, I tested 41mm, 44mm and 55mm tires on the same gravel road with 1 inch rocks. The most pleasant was obviously 55mm. Even 41mm wouldn't compare though is more plush than 36mm (some tires marked 38c are actually 36mm). If I didn't want a squishy feeling but wanted to at least survive potholes then 36mm would be my minimum. (I did see a video however on Youtube by pathlesscycled where he said 40mm was way softer on cobblestone roads then 35mm.) The Schwalbe Green Marathon tread pattern is probably my favorite on paper even though I haven't tried it yet.