The Covenant is presented as a voluntary arrangement which will not affect the autonomy and governance of provinces, whether or not they sign it.
In reality, however, the intention is to treat non-signatories as less Anglican, or as some documents put it, 'second track'. In 2006 the Archbishop of Canterbury suggested that the relationship between the two sets of provinces would be 'not unlike that between the Church of England and the Methodist Church', which seems to imply that those not signing would not be considered Anglicans at all!
This is confirmed by the Covenant text. The Introduction (§5) states that 'To covenant together is not intended to change the character of this Anglican expression of Christian faith', but whatever the intentions, the small print does. By signing, provinces will affirm that 'recognition of, and fidelity to, this Covenant, enable mutual recognition and communion' (§4.2.1). Until now, in the absence of any signed covenant, 'mutual recognition and communion' have applied to all Anglican provinces; it is only in the last few years that the campaigners against the North American provinces have undermined it. To sign the Covenant is therefore to side with the schismatics and affirm the innovation that 'mutual recognition and communion' depends on 'recognition of, and fidelity to, this Covenant'. Until now it has not depended on any such thing.
Similarly signatories will commit themselves to the view that the Covenant is 'foundational for the life of the Anglican Communion' (§4.1.2). To call it 'foundational' is a strong word, making quite clear that it is essential for membership of the Communion: in other words, that the signatories will no longer consider the non-signatories part of the Communion.
In any case there remains any doubt about the matter the power to exclude has already been pre-empted: in June 2010 the USA was excluded from an ecumenical committee on this basis, even though the Covenant is a long way from coming into force.