The possibility that ACTA would not come into force is one of several possibilities that I mentioned in my paper "WIPO and the ACTA Threat", forthcoming with the International Journal of Technology Policy and Law and published in a previous working-paper version in the PIJIP Working Paper Series.
If the agreement does fail to come into force, it would be more good news for the World Intellectual Property Organization. ACTA was a treaty negotiated outside of a true multilateral framework - an agreement made behind closed doors on an invitation-only basis. WIPO's Director General has called ACTA "a bad development" for WIPO and broader multilateral processes, a response to multilateral institutions' weakness and recnet inability to conclude broad-based treaties. IP-Watch reports progress in the recent negotation of a new audiovisual treaty, calling this 'a boost' to the multilateral intellectual property system. Another agreement for visually impaired also seems to be progressing well.
A boost for WIPO is relatively good news for weaker parties who had no voice in the development of ACTA but who do have some voice at WIPO.
Update: IP-Watch has an interesting article on where WIPO stands on its enforcement activities.