Would number of transactions change if a year from now mining was 1/10th what it is today, or 10x what it is today? Nope.
You have the causality all wrong.
Amount of mining depends on amount of transaction fees, not the other way around.
With no block subsidy, if the amount of txs drops 10x, then there will be 10x less rewards available for miners (actually even less if you go from (nearly) full blocks to never full blocks) and so mining must decrease 10x to remain profitable.
It's worrisome that senior members can get such a trivial implication all wrong.
A block can contain 4,000 transactions, or it can only contain 1 (e.g., mined right after the previous). Furthermore, a block that took very little time to be mined likely used less energy than one that took longer, while both blocks can have the exact same number of transactions.
Of course I'm not talking about individual blocks, but about longer term trends.
I'm also (like the poster I replied to) talking about on-chain transactions only. With L2, the number of off-chain transactions becomes completely unrelated to everything, as you could do a trillion off-chain transactions for 2 on-chain ones.
Sorry but you've still got this all wrong. Again, number of transactions has no relation to the amount of energy used for mining. There is zero relationship there.
Blocks are always going to be filled up no matter how much energy is used to mine those blocks. You're confusing number of transactions with cost of fees. Fees have to do with the size of transactions and how many transactions are trying to get into the block, not how many transactions are actually put in the block, because that second number essentially stays the same. We can safely assume that Bitcoin blocks will continue to be filled up in the future as they have been for the past like 6 years or whatever. So there is no real change in the amount of transactions happening per block.
If the case you are trying to make is true then mining would simply stay static forever once the block reward is done and mining only gets transaction fees. Obviously that is not the case. Energy use will go up or down with how profitable Bitcoin mining is. That relies on how many people want to get into current blocks and what the price of Bitcoin is, and then of course on the miner side things like price of electricity, efficient of mining machines, etc. Nowhere in that equation is the number of transactions.
During periods of Bitcoin mania when everybody's making transactions, electricity that goes into mining will go up even though no more transactions will be getting processed on-chain, because fees will go up. In slower periods the same number of transactions (or more exactly, amount of data per block) will be getting processed but if the mempool isn't bursting transaction fees will be low and therefore electricity used will likely go down.
Again this is why education is so important. If you can't get this right how do we expect the casual politicians and voters and investors to understand this stuff?!
This is why it's important to state over and over and over again that any calculation done about energy per transaction is wrong and simply a nonsensical calculation to make. Now and into the future.