All of this is moot, as the SCOTUS has declared secession unconstitutional. Like it or not, right or wrong, they are the current authority when it comes to constitutional matters.
Where do you get that from? There is nothing in the Constitution which prevents a state from being expelled, so your talk about secession and new republic is ridiculous. We aren't forming a new republic, we're expelling Massachusetts from our existing one. So we just do it. Tell Massachusetts that they are no longer a state, redo the flag, put customs posts around the border, cut off social security payments, etc., and it's done. Hell, we wouldn't need 49 states, just a majority vote in Congress to pass the legislation cutting off Massachusetts from the rest of us. Why isn't it as easy as that?