On blockage

Eric is right to note that most scenarios involving party disappearances or mergers would result in relatively little change in Canada's political stalemate. But he also confirms that there's one what-if which would make a world of difference:

The Bloc was born out of the failure of the Meech Lake Accord. Had the accord succeeded, it is plausible to assume the Bloc Québécois would never have existed.

In such a case, the social democratic NDP would take the place of the social democratic Bloc Québécois in the province, winning 30 per cent of the vote in the next election. The Liberals, at 29 per cent, would not be far behind while the Conservatives would take 24 per cent of the vote. This would result in the NDP winning 34 seats in the province, most of them coming in francophone Quebec outside of the two main cities. The Liberals would win 23 seats, mostly in and around Montreal and in the Gaspé, while the Conservatives would take 17 seats, concentrated around Quebec City and the Saguenay region.

Using current projections for the rest of the country, this change in Quebec would boost the Tories to 146 seats nationally, still short of a majority government. The Liberals would win 104 seats. With more than half of their caucus from Quebec, the NDP would win 57 seats. It would give the Liberals and New Democrats the possibility of forming a majority coalition.

Of course, many a commentator has looked silly for predicting the end of the Bloc over the years. But it's worth noting that the Bloc looks to be the one opposition party whose share of votes and seats would lead to an almost certain change in government if distributed along current voting lines - and wondering whether a strong message about the need for progressives to work together inside and outside Quebec (regardless of the party structures involved) might serve to get things moving in that direction.