SCOTUS said that takings for economic development could be allowed, not that they must be allowed. Kelo et al were saying the takings were unconstitutional, but the Supreme Court disagreed (I think wrongly). This means that states can take private property and transfer it to another, but if states pass a law to limit their power, there is nothing that would be unconstitutional about that.
But the multinationals can have that arbitrated at the WTO.