This is my read on it too. The Enterprise topping out at warp five, instead of warp four, would have been a major break-through. But it meant a ship going twice as fast, not ten or a hundred times as fast. The Enterprise was the NX-01, of the NX class. The ships that came to her aid in The Expanse (Intrepid and two others) could have been of the NW class, with the lead ship in that class being the NW-01. Jean-Luc Picard: "Plenty of letters left in the alphabet." Theoretically, on paper, yes. In actuality Japan continued after the war to possess a large military force. Today it has the second most powerful on East Asia, only China's is larger. And both of them existed with the "New United Nations." Each with a different collection of Earth nations. Or some nations being member of two (or all three) organizations. From the Trek history we've been presented with, the New United Nations and some version of United Earth did exist at the same time. In the mid 22nd century, how many self proclaimed "world governments" were there anyway? Do you remember what year this was to have been? Four if you also include South Sudan. Depending on what you view as "a nation," the number of nations on Earth today could be as high as 250. But that ship only existed in an alternative universe.