I think you're right about the potential for the NDP in London North Centre - there's a poll map on here somewhere. I think it the result was mostly to do with vote splitting. Probably similar to Scarborough Centre.
Vote-distributionwise, LNC isn't quite a SC situation--the polling patterns were pretty flip-a-coin helter-skelter in SC, while LNC is rather emphatically divided btw/the Tory/anti-NDP-leaning north and the NDP-voting south, with the Liberal base in '11 heaviest in the university and "professorial class" affluent midriff. (Interestingly, in the most heavily NDP parts, the Tories clear second-place advantage over the Liberals--a bit of a "Reagan Democrat" effect there.)
Of course, redistribution will make everything a whole new ballgame by 2015, which may put an added fresh-start ball into the NDP court--though at least for the sake of full democracy (and besides, three-way races a la LNC and SC are fun), I still wouldn't rule out the Grits, particularly in the event that former MPs bid for a comeback...
