It has nothing to do with the issue rate of Bitcoin, frisbee-on-the-roof is potentially a real problem.
Say Bitcoin crashes down to $1 tomorrow, such that it's no longer profitable to mine. A bunch of miners go dark. What happens to the block time?
Now remember that difficulty readjusts every 2016 blocks. If there are now 1% as many miners, that means a 1000-minute blocktime and potentially up to 1400 days per adjustment period (average of 700).
In this situation, the only option would be a hardfork to bootstrap the network back to a live state, either by directly adjusting the difficulty or by readjusting more frequently and more aggressively.
Say Bitcoin crashes down to $1 tomorrow, such that it's no longer profitable to mine. A bunch of miners go dark. What happens to the block time?
Now remember that difficulty readjusts every 2016 blocks. If there are now 1% as many miners, that means a 1000-minute blocktime and potentially up to 1400 days per adjustment period (average of 700).
In this situation, the only option would be a hardfork to bootstrap the network back to a live state, either by directly adjusting the difficulty or by readjusting more frequently and more aggressively.