I wonder, when Tesla unveils something that doesn't fit within the parameters that those people think of as a 'car', how many will drop their reservation? Since we don't know the details yet, we don't know how much of a departure it will be.
I doubt that the demographic that pre-orders a Tesla Model 3 (years before shipping), is a demographic that is unwilling to embrace change. I also doubt that it will have no manual control mode, so it shouldn't an issue regardless. Tesla is clearly going the route of being a strict super-set of the capabilities of other cars, until the market decides what features are obsolete many years down the road (e.g. steering…
Obviously, this is all speculative since they haven't revealed what they're talking about.