What are ETH miners going to do with all of their machines anyway? Just start to mine some other coins?
I know some other people commented on it, but just for anyone unaware of how mining rewards work for some crypto and how switching to other coins probably won't help miners long term:
In real simple terms, a lot of crypto has what's known as mining "difficulty". A lot of crypto (like bitcoin) is set to only issue a finite amount of the coin before eventually there are no more rewards to be had. In order to stop people from brute forcing through the entire planned amount by piling a massive amount of resources into miners, a dynamic difficulty system can be put in place that scales to the amount of mining going on in the network, ensuring the constant drip feed of mining rewards as planned.
You can see it as:
Examplecoin is designed to ensure that 10 coins are issued as mining rewards on average every 1 hour. These rewards will (statistically) be divided amongst the examplecoin miners relative to their contribution to the overall mining amount. So if user 1's miners represent 10% of the overall mining workforce, he would expect to see 1 coin every hour. If you had 10 users each representing 10% of the total mining workforce, each would expect to see, on average, 1 coin per hour.
If an 11th user decided he wanted to join in, with a mining rig equivalent to the previous 10 users, he's not going to get 1 coin per hour, because now there are 11 miners evenly contributing, so they each only represent roughly 9% of the total workforce, and now are only going to get 0.9 coins per hour. The network will scale the workload higher to ensure that the 10 coin per hour benchmark is maintained.
The more and more users you pile on, the lower and lower your percentage of the take will get relative to everyone else. If you had 100 users of equal mining strength, now you're only 1% of the workforce, and since the system is designed to dynamically scale the amount of mining power required to ensure that the rate of 10 coins per hour is held, you're only going to get 0.1 coins per hour.
You might realize that 0.1 coins per hour isn't actually enough profit to offset your electricity costs, or would take an astronomical amount of time to recoup your investment on buying the card and you simply consider it "not worth it".
At that point, selling the card is probably going to get you the greatest return if you can do so before the flood of used cards hits the market and tanks the prices.
But there's a psychological component to this that makes you want to continue mining, because if "other" users start dropping out because they think it's unprofitable or unsustainable, "your" share of the rewards is going to increase and potentially cross back over into profitable territory. Switching to another coin (if enough people do it en masse) will just cause it's profitability to drop due to the increased amount of a workforce, and you're back in the same boat. So you commit to mining the coin you're already mining, in the hopes that other weaker willed miners go the route of selling their cards.
So right now miners are sort of playing chicken with each other, since they know "some" people aren't going to be able to weather the storm and decide to get out, and that's potentially going to put them back in profitability territory, but the longer it goes on the more likely they'll become that person if things don't turn around.