The New England states will do surprisingly well, in spite of the St. Lawrence Seaway tearing open. Continental rip, which happens along the African rift valley as well, is not as traumatic as subduction or when plates press into each other. It is a release of tension, allowing a stretch to lose its grip, and thus the land will pop up a bit, increasing elevation. The climate will remain steady, temperate with cold winters, so will not hold surprises for the residents. As with the development of the Finger Lakes in New York State, Lake Champlain is evidence of the lift in this area as the Seaway splits open. You will not be inundated, though your lake and river draining it may widen.