There's also a consensus that the party should move toward the centre and away from the centre left where Dion took it (sorry Earl)
...uh... Suicide Squad?
The path (even further) towards the centre is the path towards where oblivion becomes, not a certainty (the party has survived for too long for that), but at least an option. Just ask Paul Martin. Just ask Palmer.
A Liberal majority requires keeping the NDP down. That requires a leftist course (and a charismatic leader).
EDIT: Turner. Not Palmer. How embarassing.
Meh. Damn bland random surnames.
Martin and Turner lost because of their poor organization and bad luck of rising to power at the time when the public was souring on the Liberals overall, not because they were centrists.
The Liberals didn't lose this election because they weren't leftist enough. They lost way more seats to the Tories than to the NDP and, Northern Ontario notwithstanding, they lost (or failed to win back) in places where centrist voters were the deciding factor.
Liberals bleed support to the NDP (and Greens, now) not because of a sudden leftist reawakening among Canadians, but because they're weak overall: poor leadership, scandal, fatigue, bad economic stewardship (in the 70s and 80s, less so now). Voters get tired of the complacency that characterizes long stretches of Liberal tenure, so they move their vote elsewhere. The Tories are the main beneficiaries of this disillusionment, as centrist voters switch sides; this overall weakening of the coalition that elects Liberal governments frays the left flank of the party which moves toward the NDP. Once the Liberals regain credibility among centrists (who then abandon the Tories), they regain the support that they lost to the NDP without really having to work at it. My theory for this is that because the NDP can never deliver on its promises by forming a government, its erstwhile-Liberal supporters get frustrated and look elsewhere.
Electoral dynamics aside, my point is that the left isn't as crucial to Liberal victories as the centre-left/centre is. Look at 1997: the Liberals lost support on the left to the NDP, who picked up seats across the country, especially in the East: but the Liberals were still returned with a majority, albeit a slim one. They held onto the centre, almost sweeping Ontario and gaining ground in Quebec, so they stayed in power. They didn't lose any real power until 2004 when scandal and an undivided, credible rightist party emerged and started competing for centrist voters.