Without the Constitution, we would likely have been spit apart and devolved into smaller nations or re-absorbed by England.
New York and Massachusettes were open to that. It was the war of 1812, which showed we were a United Country to the rest of the world and made England live up to its treaty terms.
During the War of 1812 Massachusetts, Connecticut, New Hampshire, Vermont and Rhode Island considered secession and aligning with Great Britain while we were at war with them.
Actually they had been toying with secession even earlier, starting with the election of Thomas Jefferson.
See ‘Essex Junto’ and ‘Hartford Convention’ for the background.