I am not sure that I agree with your way of looking at it. I think it comes down to the boats ability... not equilibrium(granted I do not know any boat that can safely sail in 150 knots of wind). I can not think of any boat that has as much freeboad/mast and standing rigging that equils the amount of sail area possible. therfore there will never be equilibrium from that. Your forward momentium is driven by your boats ability to stay perpendicular to the water as the wind increases your ability to stay up in return decreases your power in your sails which will slow you down.
I used 150 knots as a outrages extreme so that one could clearly see no standard boat could make headway in such a storm, and there must be a point where a sailboat cannot make forward motion against a certain wind speed. As wind speed increses, you must reef (reduce sail) so there could be a point where the wind friction of the rig and boat is greater than the forward force gernerated by the sail. Also, the actual force acting to make a sailboat go forward is a small fraction of the total forces acting on the boat- that is why there is a keel, to counter the leeward forces.