I am waiting for a state or group of states to make a break for it. F this union.
Texas, Oklahoma, eastern Colorado, Kansas, Nebraska, Utah, Wyoming, Idaho, Montana, South Dakota, North Dakota would make a decent country... plenty of minerals, agriculture, and access to the Gulf of Mexico.
I would expect in that scenario, for southern California and New Mexico to break off and become part of Mexico. Arizona, I am not sure of. Washington, Oregon, and northern California would be suitable additions to Canada.