IMO, the Constitution is still the law of the land and States may not supersede its basic tenants....but is 2016 after all, let's party!!
My point is that if or when they do act counter to the constitution, there's only one place to go to have it corrected.
And I believe it is likely one or more states will not allow Cruz access.
He would not have been able to obtain ballot access in Texas when he first ran as a Senator if he had disclosed he was a Canadian citizen, and would probably not be able to do so today if he still were.