Flying YYC->ORD->AMS today, and it made me muse about the following.

Today the checked bags of all planes arriving from Canada and connecting onto another flight are re-screened. However carry on bags and pax themselves are generally not re-screened unless the connection requires a change to a unconnected terminal (or if the Canadian airport does not have US CBP pre-clearance). In my case, UA metal all the way, YYC has pre-clearance, so I won't be rescreened when I get to ORD. If the TSA is unhappy with CATSA's checked bag screening, then should it not be as unhappy with CATSA's carry on bag and pax screening?

If the TSA then re-screens pax from Canadian airports with CBP pre-clearance, then this might make Canadians and thus their government, wonder what benefits they are deriving from pre-clearance.

Thus I am predicting that the TSA will eventually re-screen pax who arrive from Canadian pre-clearance airports, and this will in turn end pre-clearance. As it took me 1.5 hours from the time I arrived at YYC with BP in hand and no checked bags to the CBP stamping my passport, I won't lament the end of pre-clearance, and the death of NEXUS.