Eh, I'm not sure I would call any scenario that allows Irma to reemerge out in open water a best case scenario in the case of the 00z Canadian. Granted, we wouldn't be talking about a Cat. 5 monster, but who knows for certain what Irma has the potential to do in the GOM if the environment/conditions are favorable enough for re-organization. Even moreso if Irma's core isn't completely disrupted crossing Cuba.
Case in point: Harvey. It went from a tropical wave to a Cat. 4 hurricane within 48hrs in the GOM.
That's just my two cents though.