I would hope that Porter is profitable. I've flown with them four times, and have always liked their service. (Though last year flew Porter to EWR and Air Canada back, and found AC to be just fine).
My only concern is the expansion. Though I go to Sudbury quite often, I'd never dream of flying there. To be honest, I'd rather take the Ontario Northland local bus (I've taken Greyhound once to Sudbury, and am not in a rush to that again, but I found the slightly longer ON trip to be very pleasant). The airport is a long way from the city core. Halifax's airport may be farther, but at least has the 102 freeway connecting it with airport shuttles, which Sudbury doesn't have. The Chicago flights I have been on had low loads. So I some concern about the expansion plans - that's what killed Canadian airlines before, like Canada 3000 and Royal and Jetsgo. It could work this time, now that Porter has a decent set of possible connections at YTZ, and the Q400 is a good aircraft for this type of operation, but I wouldn't be buying any stock in it, as much as I've been converted into a fan of the airline.