If there is no further extension by the CBN for Nigerians in diaspora, a large number of people are about to be cut off from the Nigerian banking system. The CBN has engaged a vendor to undertake the BVN registration for Nigerians abroad and also allowed some banks with branches abroad to also undertake the BVN registration.
However, these efforts have largely been focused on people in a particular region and there are still a lot more people to be reached.

What is the way forward?
Sometimes, we like to make something that is simple very complicated in Nigeria.
A solution will be for the CBN to work together with the Nigeria Immigration Service (NIS).
Nigeria started issuing the E-passport around 2009.
The E-passport has helped to reduce the incidence of people using multiple identities to travel across the Nigerian border and a databse of all passports issued and travel history is maintained by the NIS.
Once someone applies for the E-passport, it is very difficult to change any details on it except there is a very cogent reason verifiable by the Nigerian Immigration Service.

I propose that Nigerians in diaspora who have bank accounts in Nigeria be allowed to send their international passport datapage to their banks who will send same to the CBN for verification. After verification by the CBN from the NIS that the bank customer is not in Nigeria and has not been in Nigeria since September/October 2015 when the deadline expired.

A temporary BVN can then be issued which could be valid for five years or even ten years with a proviso that Nigerians in Diaspora register for the main BVN anytime they are in Nigeria before the expiration of the temporary BVN.

I hope this makes sense to the relevant authorities.