That said, I think both are pretty unlikely, assuming no big changes to the code. Very hard to secure the network at that pricepoint, without building many many power plants...
Have you actually done the math on that? Based on hash rate trends, where would you expect the hash rate to be in the case of million dollar BTC?
There's also the renewable energy infrastructure to consider. Solar panels and wind energy continue to get cheaper. And what if Bitcoin ends up taking a big bite out of the gold market? If the gold market shrinks, we'll see lots of energy-intensive mining operations shut down.