Incorrect. A draft, if any draft is activated, will come about through an act of Congress, signed by the President. If at that time it is decided that it is in the best interest of the country not to include women in the actual draft, then the law will be written in that manner.
Except that the principle will already have been established in law that women are liable for the draft. To then exclude them would be to make an exception of the then established law. And what is the point in having women register for the draft if they would be exempted from any real draft?