What prevents most of the miners reject such a block? Nothing. You took have an hour to verify this block, only to find out that the main chain already extended by 3 blocks and this block is orphaned, what is the point?
So as a new user joining the system, I'm not allowed to mine the blocks that I want (within the block size limit)? Don't you see how idiotic this is?
The global average does not make any sense. You need only 7000 enterprise level 1Gbps full nodes and mining nodes to keep the system decentralized, and rest of the slow internet user can just use SPV nodes. And you can already do it today. In 5 years, those full nodes can be upgraded to 10Gbps
You are the one who isn't making sense. I have no idea why ICEBREAKER even lets you spread nonsense here. People who run nodes don't really have an incentive (aside from businesses and miners?) to spend even more money on them. Even if we disregard the cost in advanced countries, exactly how do you plan that node operators in third world countries to upgrade to 1 Gbps (not to mention 10 Gbps)? Oh right, they don't matter for you (IIRC you mentioned the network being okay with 100 nodes; I could be mistaken).
Are you going to provide the funds for this network-wide upgrade?