The block size limit is not the same as real block size. Even if you remove the limit, it does not mean miners will mine 100MB blocks, there will not be so many transactions with fee in 10 minutes. Attackers can send 100MB blocks but that will be rejected by miners immediately.
What prevents somebody from becoming a miner and mining such a block? Nothing.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?
I don't think we have ever reached the network bandwidth bottleneck. With an average 70% increase in transaction volume per year, the network will be fine at least for another 5 years, and by that time, 4K/8K TV rolling out will make the average home bandwidth jump to 1Gbps to be able to get 8K live broadcast
Global average in 2015: 5.1 Mbps; and you're trying to sell us the story that the global average will be 1 Gbps in 5 years (i.e. 200 times more)? 
Just stop.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