A fixed wing drone only needs one motor, the control is easier, and the physics are more favorable for carrying high ordnance. I'm skeptical that this is going to change much.

It's cool in that it can hover and do quadcopter type flight with only a single motor, and it's that second part that is interesting, because a fixed wing can also do a prop hang, but it can't do quadrotor-like flight from there.

It's usefulness is likely to be in other areas -- mainly applications where that flight mode is important.

A fixed wing drone needs at least one extra motor for the control surfaces. More likely two or three.