According to existing Supreme Court precedent[1], nationalization of companies requires approval by Congress, not just the President, so that would make it more difficult.
According to existing Supreme Court precedent, the president isn't able to impound funds which had been allotted by Congress (line item veto) [1], or fire the head of an independent agency for reasons other than allowed by Congress [2], it doesn't really seem like precedent has much weight amongst those in power today.
[1] https://en.wikipedia.org/wiki/Youngstown_Sheet_%26_Tube_Co._...