Think of the value of Bitcoin over time as the total value of the energy input in the mining network, divided by the subsidy + fees.

In general, if Bitcoin is $X that's because about $X * (times) the mining subsidy is being spent on all mining facilities combined, including staff/equipment/rent/energy costs, every 10 min globally.

This grows about 15% a year (the average growth seen from 2018 to 2024).

If we take the current mining cost of $90k per coin, then the value paid to the network by miners per Bitcoin block today is $281,250, by 2028 that will grow by 1.15^3 = 1.52.

1.52 * $312k = $427.5k per block.

Since the subsidy reduces to 1.5625 in 2028, that means $474k / 1.5625 = $273.6k per Bitcoin as far as production cost goes.

We can't forget to add in dollar debasement though, since they debase on average 6.8% a year, 1.068^3 = 1.22.

1.22 * $273.6k = $333.8k.

Jan 2028 Bitcoin will likely be worth around $333.8k or higher.

The current price is not $90k as it's a bit overvalued though, which makes sense as we're beginning a bull year which will end in a FOMO peak and FUD crash.

So just take the same number of $333.8k and multiply by 1.11, assuming the price is similarly over valued as it is today, and we find the estimated average mining cost in Jan 2028 will likely be $370.5k per Bitcoin.