The energy consumption has grown because the reward has grown
This is a very good point. It's also worth mentioning the halvings; meaning not only are ASIC improvements going to hit a certain performance wall, also the rewards will get lower, pushing down the amount of miners running. So effectively, the power consumption will always be bound to price/coin and coins/block.
but it wont push down the number of miners running. because there are many factors at play to keep them interested
EG
if bitcoin transactions were stuck to only doing say 4000tx/block and each tx was 250bytes at 10sat a byte for the next 15 years at total of 0.1btc a block in fee (1mb tx utility(witness scalefactor cludge))
2024 Reward 3.125 fee 0.1 = 3.225
2028 Reward 1.5625 fee 0.1 = 1.6625
2032 Reward 0.78125 fee 0.1 = 0.88125
2036 Reward 0.390625 fee 0.1 = 0.490625
yea your thing oh no. miners will stop mining
BUT imagine if bitcoin transactions were NOT stuck to 4000tx/block at 10sat a byte for the next 15 years
2024 Reward 3.125 fee 0.2 = 3.325 (8000tx at 10sat/byte (2mb actual tx utility))
2028 Reward 1.5625 fee 0.5 = 1.9625(16000tx at 10sat/byte (4mb actual tx utility))
2032 Reward 0.78125 fee 1.2 = 1.98125(48000tx at 10sat/byte (12mb actual tx utility))
2036 Reward 0.390625 fee 1.6 = 1.990625(64000tx at 10sat/byte (16mb actual tx utility))
as you can see the amount of coin available per block to pay miners can still go up(via fee's)
and this does not need people to "pay more" individually. which would shy away alot of people from using it.
instead it would be more people, collectively pay
also factor in a variable of if bitcoin prices were to go up by 2x and tx count was to 2x
now reward 6.25 fee 0.1 = 6.35=
$254k (btc=$40k)
2024 Reward 3.125 fee 0.2 = 3.325=
$266k (btc=$80k)
2028 Reward 1.5625 fee 0.4 = 1.9625=
$314k (btc=$160k)
2032 Reward 0.78125 fee 0.8 = 1.58125=
$506k (btc=$320k)
2036 Reward 0.390625 fee 1.6 = 1.990625=
$1274k (btc=$640k)
as you can see there are alot more variables that can keep miners interested. not just fee's but also the bitcoin price.
aswell as how even if some technical limit stops how small an asic
chip can get vs watts/thash
people can still just multiply the number of physical mining rigs or more people can mine for a slice of the $1.174m compared to a slice of a $254k