[brandonsometig]

You need a second layer(and possibly more on-top of that) for several reasons.

How do you expect to propagate and store 1GB blocks (hell, even 100MB blocks) every 10 minutes for the foreseeable future. I understand that the cost of storage and bandwidth has been falling for some time however if you want this system to gain 'mainstream' adaption it cannot everyone's coffee purchases for the rest of time. How do you keep a system like that decentralised if you aren't even paying people to run these nodes? There certainly wouldn't be as many as there are currently.

In a world of 1GB blocks and ultra cheap transactions it means people can simply use it as online storage. You could upload your movie collection and have it propagated to all of the nodes on the network.

The internet would not have scaled if we still broadcasted every single packet to all of the nodes on the network, it had to be split up and routed and the very same will happen to Bitcoin.

[sparkie]

Extremely large blocks will require the big miners to all host their servers in a ULLDMA-like facility, because low latency block propagation gives them the advantage. Anyone not in the club will suffer high-latency block propagation which will put them at a disadvantage to the other players who are all hosted in the same physical location. The result is that a single-point of failure in the system will come not from the concentration of mining power, but the concentration of block-propagating servers accounting for the majority of mining power.

There are obvious questions like who will run such facility, who will be able to join, at what price, and under what jurisdiction will it be. If the club is run collectively by the largest miners, they would not be incentivized to let any new competition join the club as it would collectively harm the existing members who have the advantage.

Also, in existing trading markets, we've seen that there's an "outside club" that can pay to host servers in these facilities, but there's still an "inside club", who get the data earlier than the outside club. (https://www.cnbc.com/id/100809395)

[brandonsometig]

At which point you may as well put the transactions in a SQL database and call it Paypal.