Arresting and sending all of Congress to Gitmo will immediately collapse the stock market. It would be the biggest/fastest drop in history. Probably drop 95% overnight.

There would be mass riots and civil unrest like never seen before, power blackouts, food shortages, looting, etc.

If it happens, its going to look like Armageddon for a while so if you really believe he's going to arrest nearly the entire government be prepared and stock up on food/water.