There is even a risk that bitcoin will come to a standstill, stuck with a high difficulty and not enough hashrate to solve new blocks.
No, there is no such risk outside of mental exercise. For more information, see:
Increasing Zero towards unreachable difficulty ?Cant the difficulty go down?
Yes. The difficulty adjusts up
or down depending on whether blocks are being found faster
or slower than the intended rate (2016 blocks every 2 weeks). See:
https://en.bitcoin.it/wiki/Target