I sorta agree with Josée Legault that M-V won't be that important for the PQ. Either they're comatose like Joe Clark's PCs or die completely like the UN, and I don't think another leader would do much better than PSPP.
Its interesting to look at formerly powerful parties in Canada that have died. The classic example is the Union Nationale which went from being the government of Quebec in 1970 to losing all seats in 1973 and after a dead cat bounce in 1976 - basically ceased to exist.
Other major parties that have died would include:
Alberta Social Credit (Government 1936 to 1971, sputtered with a handful of seats in the 70s and then vanished)
BC Social Credit (Government 1952-72 and again 1975-1991 - then got annhilated and subsumed into the current BC Liberal Party)
The provincial Liberal parties in Alberta, Saskatchewan and Manitoba were all going concerns as recently as the 1990s and 00s - and are all now basically dead.
Saskatchewan Progressive Conservatives as well
