I can see how a badly divided left would benefit the Conservatives.
There are some Conservative-NDP marginals in western Canada (the "rurban" Saskatoon and Regina seats other than Ralph Goodale's (Liberal-Wascana (& southeast Regina)), all presently held by Conservatives, come to mind, although some of them may not be very marginal nowadays), where the Conservatives could be hurt by a Liberal -> NDP shift, although a lot of would-be Liberal voters there might vote tactically NDP anyway, just as I'm sure there are tactical Dipper votes for Goodale in the Wascana riding. I imagine the NDP percentage in there would surge if and when Goodale retired or in the first election after the Conservatives took him out.