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A 10 speed 10 -36 rear cassette that works with the XD Driver body. Then you could run a smaller chain ring losing top end speed while keeping the lowest gear easy enough.
Patent law probably has something to do with it. Plus why would you want less range?
Canfield did a 9-36t compatible hub using part of a Capreo cassette.
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I wouldn't have thought it would have less range than a 10 speed 11-36 cassette. and surely it would work out cheaper than converting your bike to an 11 speed which would require the XD driver, cassette and shifter and mech compared to just the XD driver and a cassette if it was 10 speed.
I just thought it would be a way to keep the high gear and get a low easy gear without having to fit a massive 40/42 ring which seems to stretch the capacity of several mechs to (or beyond) their limits.