When the internet speed is very fast for all the miners, the benefit of smaller bock (fast block relay speed) will diminish. All of them will include more transactions.
It's not only the internet speed. The network, which means all of the miners, have to verify blocks and the bigger the blocks the higher the time needed to verify them. Which means bigger blocks need more time to confirm.
I thinke the best way to solve this is more transactions, so higher fee and dropping block reward.
Does it mean we have to have fast CPU or powerful computer to do that? Is that required for ordinary Core wallet holders?