If those people (i.e. people with 1Mb/s internet) are totally unimportant, why did they form the central component of your previous argument
There are different statements, and arguments for these statements, which are mixed here.
The first statement is:
"The claim that, for a crypto currency based upon PoW leads to centralisation, is bogus".
The example crypto currency can be a HYPOTHETICAL bitcoin with 32 MB blocks, or any other crypto currency with free block size. This is where I argued that:
1) as long as the miners agree and make only one block chain, nodes can only copy that block chain, there ain't any other around. So whether there are LOTS of proxy servers (nodes), or just a few, doesn't matter, what matters is the miners that make that chain. Users only need to access A node with their wallets, and *if they really want to, for themselves, can download the entire block chain to verify*.
2) even 32 MB blocks every 10 minutes doesn't require extra ordinary computing and network equipment as of today.
Mind you that we are not talking about the real bitcoin of today, but about a hypothetical bitcoin, or another crypto, with blocks that can be 32 MB.
The second statement is:
"Given that the actual bitcoin protocol is blocks of 1MB, and that the only agents capable of modifying this, are miners (they make the blocs !), in order for this potentially to happen, there has to be a huge consensus between miners to do so, and to do so with the same protocol change ; this won't happen, because there is NO incentive AT ALL for ANY MINER to go to bigger blocs and release pressure on the fee market".
Here, my argument is that small fish don't matter, because increasing bloc size to allow smaller fish to transact some bitcoin, doesn't increase miner revenue, on the contrary. This means that miners have no incentive, not only to get these fish to bitcoin and transact and they CERTAINLY have no incentive to try to make them do so with a 2nd tier network because these poor suckers can't even download a bloc chain.
In other words, the original lowering of the bloc size from 32 MB to 1 MB, to "allow poor suckers to use bitcoin over their 56kb lines" is totally BS. But now that that 1 MB limit is part of the protocol, the only people that could, eventually, decide to lift it, the miners, have absolutely no reason to remove that bonus for them, not with bigger blocs, and not with a second tier network.
Miners don't need small fish adoption. They want big whale usage of bitcoin, with few transactions of large amounts, and the current protocol is perfect for that. It didn't need to be so, but by error or by intend, it has been designed that way, and they would be crazy to remove this.