I can't make a "rational argument" about what people I don't know might do. I am saying that it's very much in their interest and that I would not be surprised if they do it. How about we check in here again when it happens / fails to happen?
Sure, if you think they should do it, totally valid opinion. Talking as they are going to implies knowing something that everyone else doesn't, which is why you're being challenged about it.
It's easy to make something look rational when you pick and choose axioms. The republicans don't have a rational interest in decriminalization because their financial backers don't want it, and they have moral qualms about it since 100 years of government lies convinced them it's the devil's plant.