Various news reports and blogs (including Ruth Gledhill's accessible from the sidebar here) talk of the GAFCON statement in sentences which include the word 'schism'. The use of that word is not entirely unfair inasmuch as GAFCON does talk about a new North American Anglican Province. What might be unfair is the world and its journalists judging GAFCON's leaders being solely responsible for this state of affairs.
It will only be a schism if Williams and Schori refuse to recognise the validity of the new province. If they recognise its validity then communion among all Anglicans in North America remains possible and the Anglican Communion as one entity (albeit with considerable internal tension) remains viable. Williams and Schori ought to validate the new province: Williams should be agreeable to its theology (great patristics man that he is, etc) and Schori should offer agreement as penance for the wilfully aggressive approach TEC has taken to Anglicans seeking to be orthodox in creedal and BCP faith in North America. (OK I have not mentioned Hiltz, the Primate of Canada ... Presiding Bishop Schori is the key player. Hard to see Canada not following TEC's lead).
The ball is in Williams and Schori's court.