The original manufacturer, Longbranch Arsenal (later Canadian Arsenals Ltd) was shut down in 1976 by the Trudeau government. Supposedly parts for the No.4 rifles could still be bought from Pakistan (which acquired all the No. 4 machinery from ROF Fazakerley in Britain in the early 1960s)...but apparently Ottawa doesn’t want to do that.
I talk once in a while with a couple of Canadian Forces veterans (who date back to the C1A1 era); their perspective is that this is nothing more than politicians seeing another opportunity to profit from a new contract. A problem they’re facing, though, is that the replacement weapon has to be made in Canada...and Diemaco/Colt Canada doesn’t make bolt-action arms.