It might come to that but I would prefer not. I think the way that would have the most chance of succeeding would be for Congress to simply vote that it was none of the federal government's business unless it happened on federal property.
They could do that. But, unlike alcohol, I doubt that every state would want to legalize drugs. And that would cause a major problem with the adjacent states.
That is why I thought it best that all states vote on this issue in the form of a constitutional amendment.