Parliament to date has only enacted one situation where the ownership of prohibited firearms passes from one generation to another, and that is in the pre-1946 handguns, the so-called war trophy exemption. The intent in Bill C-71 is that, in the firearms affected by this bill, like the other circumstances where Parliament has legislated to provide for grandfathered ownership, that grandfathered ownership only be available to a certain class of firearms and to a certain class of the current owners. Also, the intent is that the pool stays fixed in time, and that pool does not increase over time through bequests, legacies, or inheritance.
On June 5th, 2018. See this statement in context.