All of the trading ports in Mexico used by the Chinese and others would not be possible if the trucking industry could not easily transport to the US and Canada from Mexico.
Therefore, there will never be any retaliation, since to do so would be to ruin the stream of cash they get from having large ports which do not have the same regulations as we have in the US. It might even make some shipments be off-loaded directly into the US ports.
I'm sure they would really appreciate Mexican drivers stealing their loads back into Canada, not having to follow all the rules and regulations, licencing fee's etc. while they run empty back to Canada.