It's not a possibility, it's a matter of how many!
Simple basic math, the revenue is halved, the cost would have to be the same, obviously a lot of miners didn't have the cots less than half of what they were making.
You were getting 10 $, your costs were 2 $, now you're getting 5-2, still a profit.
You were getting 10 $, your costs were 6 $, now you're bleeding money so you turn off the gear.
As simple as that.
Regarding in of cost in mining, Bitcoin code has a feature that automatically adjust whenever the mine block time is not reach this means if blocks is getting longer than 10 mins than the difficulty will decrease thus making miners mine faster and solved blocks and getting rewards.
That is not a magic tool that somehow will make mining profitable again, it is designed to keep the block time, not the miner's profits. If the miners quit difficulty drops, it's tempting to go back and mine but if all do the same we're back to square one when they will again quit.
Let's wait and see how much of an impact this will have
630000 2020-05-11 19:23
630034 2020-05-12 02:12
That's 409 minutes for 34 blocks, 12 minutes on average!