Software wise it should be possible to make new "checker" software, so the operator has to ability to choose if 10spd or 11spd firmware is going to be installed. It just depends on Shimano wanting to make it.

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Scott Foil Di2 2012
Scott Scale 35 2010

Yeah, the question is whether Shimano wants to really push 6770 out the door, or keep 11-speed as a selling point for 9000/ 9070. In the latter case I won't touch a new groupset until 6870/ 8070 (whichever the next Ultegra is). Not going to get further invested into 10-speed when 11-speed will be bringing a new hub design. If I could stick with 10 for now and get a free software upgrade to 11 whenever I wanted to upgrade wheelset/ cassette, all the better. Either way, not dropping 9000/ 9070 coin. I can't see why there would be a hardware limitation on how finely the motor could be moved.