You're not taking into consideration the massive doppler forces that would keep the plane from lifting off.
You wouldn't move forward even if someone is pushing you if the conveyor belt accelerates fast enough to offset the force. It's harder to imagine in the rollerblades analogy because people are flexible so your feet would start dragging behind, but if you put like a bike on the treadmill and stood behind it (off the treadmill) and pushed on the seat, an accelerating treadmill could potentially negate your pushing due to the friction in the axles translating some of the treadmill force into a backwards force. I agree with you that there's no more force exerted by the conveyor belt once the inertia is broken IF the conveyor belt is just going at a constant velocity. But if it's accelerating, it would continue to apply a force.
