Canada is very rapidly heading towards a two-party system. The Greens barely count as a party, the NDP have joined forces with the Liberals, the Conservative-Reform Alliance Party is desperately trying to subsume the breakaway PPC Party, and the Bloc is specific to one province.
Every election boils down to a choice between two parties: Liberal and Conservative. When the Conservatives are too socially regressive (“barbaric cultural practices hotline”, Pierre Poilievre) many NDP voters hold their nose and vote Liberal.
If the Conservatices continue down their current path, Canada will inevitably become a strictly two-party country: the NDP will cease to exist as an alternative.