Well lets look at this very simply.
rewards will drop to 12.5 coins
then 6.25 coins
then 3.125 coins
then 1.5625 coins
transactions are 200,000 per day so 200,000 x 0.0002 = 40 coins say 150 blocks a day at 25 = 3790 coins a day and 420 a coin = 1,591,800 was earned today and what was spent on power ?
at best 1100 ph used .4 watts or 440 mega watts x 24 = 10,560 mega watts per day. at 4 cents means 422400 was spent
that would mean more then 1 million usd was made world wide. very small number as we are a small industry.
frankly my guess is power cost was more like 6 cents worldwide and eff is closer to .45 world wide
but the ½ing is coming and coins will drop to 1895 a day and no mechanism has come along to expand transactions.
200,000 a day is very small.
Okay, so lets say roughly 9 years out.
Total dart at a dart board here, but lets say we triple the total power consumption to 30,000 mega watts.
Lets say somehow that gets consolidated into 3.3 cent power.
Network cost in power alone is now $1,000,000 per day.
Currently, the revenue is a little over 3x the expense, but that can't last forever. Lets stick with the theme of 3, and say that the network will scale back if it ceases to generate 133% of power costs in mining revenue.
At 468.75 coins a day, we need price to be around $2800 a coin. Lets call it $2000 and assume the remainder is transaction fees.
Okay, that seems plausible, although I suspect the 133% is more like 200% in terms of revenue vs cost.
But lets say the price stabilizes at $1000.
Now we need to come up with ~$800,000 a day in transaction fees. At the current estimated transaction volume ($172 million per day) that means an average tx fee of 0.5%. Is that competitive? Granted, by that time, one would hope transaction volume is much higher than todays numbers.
Reality is this probably isn't going to affect the mining sector until 4-5 halvings out. And by that time, who knows.
Other folks seem to think that is central to "securing" the network, along with "decentralization" (whatever that means to you). I have no real idea as to what is required to "secure" the network, since there are a variety of threats that you could be concerned about. All of which might have different answers. I can't believe that "more expended hash" per transaction is the answer in general. It's also NOT obvious to me that the infrastructure we have today, and it's expected growth, is truly required for the current transaction volume. Right now, and probably for the next decade or more, it's all about the "block reward", and the transactions are just a sideshow.
I think the difficulty is way to high for the purposes of securing the network. It's hard for me to see what would have to happen in order to actually reduce the difficulty in any meaningful way given the current investment in infrastructure. It will have to be some gut-wrenching reduction in infrastructure for that to happen.
Frankly my biggest concern is what happens when some large entity shutters their doors and the hash rate drops significantly. Especially at the start of a difficulty cycle. Confirmation times skyrocket, and who knows what happens to the public sentiment/market.