The Gospel is everlasting (ref. Revelation 14:6).
The purpose of this explanation of the parable found in Luke 11:5-9, is to show how it is communicating the fact that everlasting life will always be available to anyone who believes in Messiah (Christ) and endures here.
This is despite the fact that the doors to the kingdom of heaven are now ‘locked’, and the wedding feast of the Lamb has ended.
It is now dark and way past midnight here, however all those who believe and continue to knock, receive grace (Revelation 14:12).