Is there going to be a model for interstate better? For example, if PA and WV both have legal betting through an app, would it be legal for PA residents to bet in WV and vice versa?
Yes, that will be permissible. The government won at every stage of appeal except the Supreme Court. The won it in the lower courts based on just what you cited above--interstate commerce. Since betting is interstate commerce, the Federal government has exclusive jurisdiction over what States can operate this business. The SCOTUS used the old State's rights argument(they call it something different now) that the federal government has no right to tell any State whether or not they can have gambling. It is the State's decision. REVERSED.