There's a limit to how high they can go (can't offer more in transaction fees than you actually have) and even before you hit that point you may encounter the b

There's a limit to how high they can go (can't offer more in transaction fees than you actually have) and even before you hit that point you may encounter the back side of Bitcoin's Laffer Curve where the expense results in lower total transaction fees per block even as individual fees rise. It's possible that point would be far beyond any conceivable price crash, though, I don't know how to put it into anything resembling concrete numbers.