Again, I don't need to disprove your theory. I only need to point out objections. If you can't defend your theory, then you don't have one. I can prove that off-network transactions exist today, if I desire. I can tell you how to do some with a MtGox account, and I've done it many times before the Silk Road was brought down. Coin-mixers do them as a matter of their primary function. All that is required for them to grow in scope is for a market force to require them. Something as simple as a percentage rise in the transaction fee would be enough. A government crackdown would certainly do it.
I told you that offchain is irrelevant to whether my attack is an attack for onchain transactions.
Just because you say it, does not make it so.
Also offchain reintroduces 3rd party risk, which means government and courts will be involved. So same result and smell, the government gets control.
It may or may not reintroduce 3rd party risk. Consumers may or may not be willing to invite government back into their economic activity. Doesn't matter, it's their choice. But if the majority of small value transactions are off-network, the majority of Amazon-cartel's transactions will have no mining value anyway.
One. Mining as a secondary effect to electro-resistive heating. I.e. you can't undercut the miner who's rig heats his flat. There is also whole threads regarding using asics embeddeding into heat cable to warm pipes.
Of free energy and perpetual motion!

I didn't write "reduced" costs, I wrote "free" costs.
Reduced costs are free costs to someone. Please respond to the effect that sero profit margin miners would have upon your theory.
Two. The Wal-mart|McDonalds|Sears alliance versus the Target|BurgerKind|JCPenny union. Competing cartels can mine at a negative profit, because they're primary business is selling retail products, not mining for bitcoins.
Great you argue against cartel attack by citing an alliance of large corporations a "free" mining option.

As if they do it for free

They would do it for free, because it would still be cheaper at scale than their current "cost centers" for online commerce security, as well as the overhead with the handling and security with regard to both credit card transactions and cash transactions today. Do you think that armored cars are costless? That IT security gurus work cheap? That Walmart puts cameras above every cash register because they trust their $7.50 per hour part time cashiers to be trustworthy with hundreds or thousands of cash dollars?
That happened long before you think, but why couldn't Microsoft gain a regulatory capture advantage over Linux? Because it wasn't a company that could be regulated, it was simply the product of a new kind of development. Open source. Which turns out to be rather resistant to regulation by governments. Bitcoin is open source, and p2p, and distributed. All things deliberately designed to contribute to it's resitance to regulation.
And what do you think I am trying to do by explaining and defending this attack?
Fix it! With open source! And you are trying to stop me!
Great logic you have there.

I'm not trying to stop you from fixing whatever you think is broken, just don't try to fis inside Bitcoin. Go start an alt-chain, and if you're right about the problem, as well as how to fix it, then you will profit. For that matter, considering your proposed fix, you don't even have to start a new coin, inflation coins without the block reward reductions already exist, and have for years. Go have fun.