When I was reading this recently it made me ask myself what law this is that Jesus refers to which doesn’t fail?  I think He means the moral law of justice, many of whose precepts were captured in the Law of Moses.  There are certain consequences named in it, some of which are prescribed social responses to certain evils, some of which are natural consequences.  I suspect that Jesus was trying to teach how absolutely inexorable justice was, with its natural and spiritual consequences, so much so that the natural world would dissolve before the law did.

Occasionally society gets corrupt enough that social consequences of evil are done away, but that doesn’t mean that natural consequences can be done away, and the more humanity tries to fight the natural consequences, the closer they get to destroying themselves.

The commandments of God are not just the way to become like God, they are an optimized way of living such that in the long run of eternity consequences will work for you, rather than against you.  They are the “house advantage” for eternal life.

From time to time it may seem as though societal consequences in favor of evil are trumping the natural consequences against evil, but evil’s half life is short.  Maybe not as short as we could wish, but a few generations (and maybe less) will bear out the truth of the matter.