In this scenario, the total Bitcoin hashrate would drop by 30-35 percent on average shortly after the halving. This scenario could already cause some significant problems, because it would increase the time for new blocks to be created up to 15 minutes. This situation would last up to two weeks, because there would still be 1,344 blocks left to the next difficulty retarget and the number of blocks per day would drop to 96. It also creates further downside risk, because miner income per day is slashed by more than half as a result. The daily reward before the halving would equal $1.5 million worth of Bitcoin. The halving brings this down to $0.75 million per day, and the extended time to mine a block further reduces this to $0.5 million per day until the difficulty retargets. This equals a drop of two thirds in miner income per day.
Lastly, the price of Bitcoin could also be facing pressure as extended block times would further limit Bitcoin’s transaction processing capabilities. Bitcoin would temporarily process 1MB of transactions every 15 minutes rather than every 10 minutes, equalling a reduction of the current block size limit to less than 700KB. If the price drops by just 10 percent, then the combined effects of this drop, the bloc reward halving and extended block times could (at least temporarily) lower miners’ income by around 70 percent per day. This may trigger the next scenario as well.