I can guarantee you that not only will a significant number of dissidents not comply, they will develop networks and methods to undermine the gubmint's attempt to confiscate all banned firearms. Hell, the gubmint couldn't even confiscate all the banned firearms before the latest mass shooting.
The fun and games has already started for modification kits, parts changes, records obfuscation, sales & transfers, "collectors", etc.
Last time I checked...heroin was illegal in Canada too.