Lock-on is going to be included. We know this. We don't know the exact mechanics at this time though.
Since I think the main point of lock-on is so newer players who are not used to playing with the Wiimote can keep their opponent on screen, what if lock-on were tied to a bounding box whos size is set by HVS? This way, you wouldn't lose your opponent, but it would force the shooter to aim by allowing the opponent to dodge bullets by moving out of the line of fire. The effect could also be feathered (transition period at the edge of the bounding box between no turning and full speed turning) so aiming doesn't become automatic in a dance of death.
No, the bounding box could be exploited in a similar way as the current lock on. Instead of having to always aim at the center, you'd only have to aim at the edge of that bounding box.
It wouldn't be AS exploitable... but it would still be there.
I've given it a lot of thought, and the solution I think is best would be to make it so When you are locked onto a person your camera moves slower away from them, and faster towards them Having less influence the closer your reticule got to them, and with most of the influence being when they are off screen.
That way, there is no 'Box', but it still would become very easy to keep them on screen. And when it comes to the point actually getting headshots or Body shots... Players would be completely on their own.
Also, because its dependent on the player turning, it would mean that the lock on would not cause the camera to jump in any way. Meaning if the lock on was a mistake, or it locked onto the wrong person, it's not going to throw you off.
Feathering the bounding box could help a little more, but the only exploit would be during a dance of death.
Well, I imagine they are probably doing something similar to this. The thing that could make it more easily exploitable than that would be if the player could make their 'Dead zone' larger than the bounding box. That wouldn't be too hard for HVS to prevent.