Best not to count on that oil lasting forever.
And Texas has had a very volatile economy tied to the price of oil and things like Enron.
For that matter, you might not want to count on that non-union thing, either. Texas is Republican because it's a way of voting against the Northeast and the West Coast liberals. With them out of the picture, you might find pro-union Texas liberals a lot stronger.
Is the economy in these states volatile or simply more commodity and agriculturally based than the other states? A knowledge based economy is great but you still need energy, the cheaper the better. And, you still need food. How much of its own food does New York state produce? Massachusetts? Maine?
I don't know how deep the non union sentiment in these states runs. I do know that a low tax regime combined with cheap energy, food, and an unfettered labor force is a recipe for dynamic economic growth.