If the states were to be given more power, such as controlling immigration and economic policy based on industry, then each state would have a government tailored to the views of its own people. Instead of a United States of America, I would propose an American Union State (AUS). A new constitution will have to be established, but it will be established based on democratic ideals that our founding fathers would agree with.
Such an attempt was made with the articles of confederation and it has an result states became corrupt due to the governments inability to stop them. Little to no money was in the treasury due to the states ignoring the central governments request to send it since the government could not tax it on our own. It had an dream of 13 continental armies but it turned into every army for itself and the central government could buy supplies but they would have to request states to send or be able to move through their territory. We have had selfish state legislatures before but if we give them more power without the governement able to give them the rod would be chilling. Also in this day in age such an change would cripple us militarily, enconmically, and politically. Instead of 50 United states we would be an mob of free willed states that would be able to do what they would like within their territory's no matter if they are prejudice, foolish or simply just butting head with another state with no one to step in today stop. We would just end up pulling each other apart making us an weaker whole. I believe the government has too much power now but doing this would end up in an upheaval. What's to stop an shays rebellion in an day of age where getting an gun is simple without having to smash into armories such had been done then.